Basic Call Handling GSM 03.18
Transcript of Basic Call Handling GSM 03.18
Page 1GSM 03.18 Version 2.1.0: February 1997
GSM GSM 03.18
TECHNICAL February 1997
SPECIFICATION Version 2.1.0
Source: ETSI TC-SMG Reference: TS/SMG-0xxxxxQ
ICS: 33.020
Key words: Digital cellular telecommunications system, Global System for Mobile communications (GSM)
GLOBAL SYSTEM FOR MOBILE COMMUNICATIONS
R
Digital cellular telecommunications system (Phase 2+);Basic call handling
Technical Realisation(GSM 03.18)
ETSI
European Telecommunications Standards Institute
ETSI Secretariat
Postal address: F-06921 Sophia Antipolis CEDEX - FRANCEOffice address: 650 Route des Lucioles - Sophia Antipolis - Valbonne - FRANCEX.400: c=fr, a=atlas, p=etsi, s=secretariat - Internet: [email protected]
Tel.: +33 4 92 94 42 00 - Fax: +33 4 93 65 47 16
Copyright Notification: No part may be reproduced except as authorized by written permission. The copyright and theforegoing restriction extend to reproduction in all media.
© European Telecommunications Standards Institute 1997. All rights reserved.
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Whilst every care has been taken in the preparation and publication of this document, errors in content,typographical or otherwise, may occur. If you have comments concerning its accuracy, please write to"ETSI Editing and Committee Support Dept." at the address shown on the title page.
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Contents
Foreword....................................................................................................................................................... 8
1 Scope....................................................................................................................................................... 10
2 Normative references............................................................................................................................... 10
3 Definitions, symbols and abbreviations.................................................................................................... 113.1 Definitions ................................................................................................................................... 113.2 Abbreviations .............................................................................................................................. 12
4 Architecture.............................................................................................................................................. 134.1 Architecture for an MO call ......................................................................................................... 134.2 Architecture for an MT call.......................................................................................................... 14
5 Information flows...................................................................................................................................... 155.1 Information flow for an MO call ................................................................................................... 155.2 Information flow for retrieval of routeing information for an MT call ........................................... 175.3 Information flow for an MT call ................................................................................................... 18
6 Principles for interactions with supplementary services........................................................................... 206.1 Line identification services (GSM 03.81) .................................................................................... 20
6.1.1 Calling Line Identification Presentation (CLIP)......................................................... 206.1.2 Calling Line Identification Restriction (CLIR)............................................................ 206.1.3 Connected Line Identification Presentation (COLP)................................................. 206.1.4 Connected Line Identification Restriction (COLR) ................................................... 20
6.2 Call forwarding services (GSM 03.82) ........................................................................................ 206.2.1 Call Forwarding Unconditional (CFU)....................................................................... 206.2.2 Call Forwarding on mobile subscriber Busy (CFB) .................................................. 206.2.3 Call Forwarding on No Reply (CFNRy) .................................................................... 206.2.4 Call Forwarding on mobile subscriber Not Reachable (CFNRc).............................. 20
6.3 Call wait (GSM 03.83)................................................................................................................. 216.4 Call hold (GSM 03.83) ................................................................................................................ 216.5 Multiparty (GSM 03.84)............................................................................................................... 216.6 Closed user group (GSM 03.85)................................................................................................. 216.7 Advice of charge (GSM 03.86) ................................................................................................... 216.8 Call barring (GSM 03.88)............................................................................................................ 21
6.8.1 Barring of outgoing calls........................................................................................... 216.8.2 Barring of incoming calls .......................................................................................... 21
6.9 Explicit Call Transfer (GSM 03.91) ............................................................................................. 21
7 Functional requirements of network entities ............................................................................................ 227.1 MO call........................................................................................................................................ 22
7.1.1 Functional requirements of serving MSC ................................................................. 227.1.1.1 Process OCH_MSC.......................................................................... 227.1.1.2 Procedure Process_Access_Request_MSC .................................... 227.1.1.3 Procedure Set_CLI_Presentation_Indicator_MSC ........................... 237.1.1.4 Procedure Set_COLP_Info_MSC..................................................... 237.1.1.5 Procedure Handle_AoC_MO_MSC .................................................. 237.1.1.6 Procedure Obtain_IMSI_MSC .......................................................... 237.1.1.7 Procedure Authenticate_MSC .......................................................... 237.1.1.8 Procedure Obtain_IMEI_MSC .......................................................... 237.1.1.9 Procedure Check_IMEI_MSC........................................................... 23
7.1.2 Functional requirements of VLR............................................................................... 387.1.2.1 Process OCH_VLR........................................................................... 387.1.2.2 Procedure Process_Access_Request_VLR ..................................... 387.1.2.3 Procedure Check_BAOC.................................................................. 387.1.2.4 Procedure OG_CUG_Check ............................................................ 38
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7.1.2.5 Procedure Check_OG_Barring .........................................................387.1.2.6 Procedure Get_LI_Subscription_Info_MO_VLR ...............................387.1.2.7 Procedure Get_AoC_Subscription_Info_VLR ...................................387.1.2.8 Procedure Obtain_Identity_VLR........................................................387.1.2.9 Procedure Obtain_IMSI_VLR............................................................387.1.2.10 Procedure Authenticate_VLR..........................................................387.1.2.11 Procedure Obtain_Authentication_Sets_VLR .................................397.1.2.12 Procedure Start_Tracing_VLR ........................................................397.1.2.13 Procedure Check_IMEI _VLR .........................................................397.1.2.14 Procedure Obtain_IMEI _VLR.........................................................397.1.2.15 Process Fetch_Authentication_Sets_VLR ......................................39
7.2 Retrieval of routeing information for MT call ...............................................................................647.2.1 Functional requirements of GMSC ...........................................................................64
7.2.1.1 Process MT_GMSC ..........................................................................647.2.1.2 Procedure Handle_COLP_Forwarding_Interaction_MSC.................64
7.2.2 Functional requirements of HLR ...............................................................................697.2.2.1 Process SRI_HLR .............................................................................697.2.2.2 Procedure Check_Parameters..........................................................697.2.2.3 Procedure Subscription_Check_HLR................................................697.2.2.4 Procedure First_Forwarding_HLR.....................................................697.2.2.5 Procedure PRN_Error_HLR..............................................................697.2.2.6 Procedure Forward_CUG_Check .....................................................697.2.2.7 Procedure Derive_Requested_Basic_Service_HLR.........................697.2.2.8 Procedure Check_IC_Barring ...........................................................697.2.2.9 Procedure IC_CUG_Check ...............................................................697.2.2.10 Procedure Handle_CFU ..................................................................697.2.2.11 Procedure Handle_CFNRc..............................................................69
7.2.3 Functional requirements of VLR ...............................................................................837.2.3.1 Process PRN_VLR............................................................................837.2.3.2 Process Restore_Subscriber_Data_VLR..........................................837.2.3.3 Process PSI_VLR..............................................................................83
7.2.4 Functional requirements of MSC ..............................................................................907.2.4.1 Process OSI_MSC ............................................................................90
7.3 MT call.........................................................................................................................................927.3.1 Functional requirements of serving MSC..................................................................92
7.3.1.1 Process ICH_MSC ............................................................................927.3.1.2 Procedure Page_MS_MSC ...............................................................927.3.1.3 Procedure Search_For_MS_MSC.....................................................937.3.1.4 Procedure Complete_Call_In_MSC ..................................................937.3.1.5 Procedure Process_Call_Waiting_MSC ...........................................937.3.1.6 Procedure Set_CLIP_Info_MSC .......................................................937.3.1.7 Procedure Derive_GSM_BC_MSC ...................................................937.3.1.8 Procedure Handle_AoC_MT_MSC ...................................................937.3.1.9 Procedure Set_COL_Presentation_Indicator_MSC..........................93
7.3.2 Functional requirements of VLR .............................................................................1147.3.2.1 Process ICH_VLR ...........................................................................1147.3.2.2 Procedure Derive_Requested_Basic_Service_VLR .......................1147.3.2.3 Procedure Search_For_MS_VLR....................................................1147.3.2.4 Procedure Get_CW_Subscription_Info_VLR..................................1147.3.2.5 Procedure Get_LI_Subscription_Info_MT_VLR..............................1147.3.2.6 Procedure Handle_CFB ..................................................................1147.3.2.7 Procedure Handle_CFNRy..............................................................114
8 Contents of messages............................................................................................................................1278.1 Messages on the B interface (MSC-VLR) .................................................................................127
8.1.1 Abort 1278.1.2 Authenticate ............................................................................................................1278.1.3 Authenticate ack .....................................................................................................1278.1.4 Check IMEI .............................................................................................................1278.1.5 Check IMEI ack.......................................................................................................1278.1.6 Check IMEI negative response...............................................................................1278.1.7 Complete Call .........................................................................................................1288.1.8 Complete Call ack...................................................................................................130
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8.1.9 Complete Call negative response .......................................................................... 1308.1.10 Forward New TMSI .............................................................................................. 1308.1.11 Forward New TMSI ack........................................................................................ 1308.1.12 Forward New TMSI negative response................................................................ 1308.1.13 Obtain Subscriber Info.......................................................................................... 1308.1.14 Obtain Subscriber Info ack................................................................................... 1308.1.15 Page MS............................................................................................................... 1308.1.16 Page MS negative response ................................................................................ 1318.1.17 Process Access Request ..................................................................................... 1318.1.18 Process Access Request ack............................................................................... 1318.1.19 Process Access Request negative response....................................................... 1328.1.20 Process Call Waiting ............................................................................................ 1328.1.21 Process Call Waiting ack ..................................................................................... 1328.1.22 Process Call Waiting negative response.............................................................. 1328.1.23 Provide IMEI......................................................................................................... 1328.1.24 Provide IMEI ack .................................................................................................. 1328.1.25 Provide IMSI......................................................................................................... 1338.1.26 Provide IMSI ack .................................................................................................. 1338.1.27 Search For MS ..................................................................................................... 1338.1.28 Search For MS ack .............................................................................................. 1338.1.29 Search For MS negative response....................................................................... 1338.1.30 Send Info For Incoming Call................................................................................. 1338.1.31 Send Info For Incoming Call ack .......................................................................... 1348.1.32 Send Info For Incoming Call negative response .................................................. 1348.1.33 Send Info For Outgoing Call................................................................................. 1358.1.34 Send Info For Outgoing Call negative response .................................................. 1358.1.35 Set ciphering mode .............................................................................................. 1358.1.36 Trace subscriber activity....................................................................................... 1358.1.37 Use existing TMSI ................................................................................................ 135
8.2 Messages on the C interface (MSC-HLR) ................................................................................ 1368.2.1 Send Routeing Info................................................................................................. 1368.2.2 Send Routeing Info ack .......................................................................................... 1368.2.3 Send Routeing Info negative response .................................................................. 136
8.3 Messages on the D interface (VLR-HLR) ................................................................................. 1378.3.1 Provide Roaming Number...................................................................................... 1378.3.2 Provide Roaming Number ack ............................................................................... 1378.3.3 Provide Roaming Number negative response ....................................................... 1378.3.4 Provide Subscriber Info .......................................................................................... 1388.3.5 Provide Subscriber Info ack ................................................................................... 138
8.3.5.1 Location information ....................................................................... 1388.3.8 Provide Subscriber Info negative response............................................................ 1398.3.6 Restore Data .......................................................................................................... 1398.3.7 Restore Data ack ................................................................................................... 1398.3.8 Restore Data negative response............................................................................ 1398.3.9 Provide Subscriber Info negative response............................................................ 139
8.4 Messages on the F interface (MSC-EIR).................................................................................. 1398.4.1 Check IMEI............................................................................................................. 1398.4.2 Check IMEI ack ...................................................................................................... 1398.4.3 Check IMEI negative response .............................................................................. 139
Annex A (Informative) Handling of an IAM at an MSC.............................................................................. 141
History....................................................................................................................................................... 144
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Foreword
This ETSI GSM Technical Specification has been produced by the TC SMG Technical Committee of theEuropean Telecommunications Standards Institute (ETSI).
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1 Scope
This standard specifies the technical realisation of the handling of calls originated by a GSM mobilesubscriber and calls directed to a GSM mobile subscriber, up to the point where the call is established.Normal release of the call after establishment is also specified.
The handling of DTMF signalling and Off-Air Call setup (OACSU) are not described in this specification.
The details of the effects of GSM supplementary services on the handling of a call are described in therelevant GSM 03.8x and GSM 03.9x series of specifications.
The specification of the handling of a request from the HLR for subscriber information is not part of basiccall handling, but is required for both CAMEL [5] and optimal routeing [6]. The use of the ProvideSubscriber Information message flow is shown in [5] and [6].
The logical separation of the MSC and VLR (shown in clauses 4, 5 & 7), and the messages transferredbetween them (described in clause 8) are the basis of a model used to define the externally visiblebehaviour of the MSC/VLR, which is a single physical entity. They do not impose any requirement exceptthe definition of the externally visible behaviour.
If there is any conflict between this specification and the corresponding stage 3 specifications ([14], [16] &[17]), the stage 3 specification shall prevail.
2 Normative references
[1] ETS 300 500 (1994): " European digital cellular telecommunications system(Phase 2); Principles of telecommunication services supported by a GSM PublicLand Mobile Network (PLMN) (GSM 02.01)”.
[2] ETS 300 523 (1994): " European digital cellular telecommunications system(Phase 2); Numbering, addressing & identification (GSM 03.03)”.
[3] ETS 300 534 (1994): " European digital cellular telecommunications system(Phase 2); Security related network functions (GSM 03.20)”.
[4] GSM 03.32: " Digital cellular telecommunications system (Phase 2+); UniversalGeographical Area Description (GAD) (GSM 03.32)”.
[5] GSM 03.78: “Digital cellular telecommunications system (phase 2+);Customised Applications for Mobile network Enhanced Logic (CAMEL) (GSM03.78)”
[6] GSM 03.79: “European digital cellular telecommunications system (Phase 2+);Support of Optimal Routeing (SOR) Technical Realisation (GSM 03.79)
[7] ETS 300 542 (1994): " European digital cellular telecommunications system(Phase 2); Line identification supplementary services - Stage 2 (GSM 03.81)”.
[8] ETS 300 543 (1994): “European digital cellular telecommunications system(Phase 2); Call Forwarding (CF) supplementary services - Stage 2 (GSM03.82)”.
[9] ETS 300 544 (1994): “European digital cellular telecommunications system(phase 2); Call Waiting (CW) and Call Hold (HOLD) supplementary services -Stage 2 (GSM 03.83)”.
[10] ETS 300 545 (1994): “European digital cellular telecommunications system(phase 2); Multi Party (MPTY) supplementary services - Stage 2 (GSM 03.84)”.
[11] ETS 300 546 (1994): “European digital cellular telecommunications system(phase 2); Closed User Group (CUG) supplementary services - Stage 2 (GSM03.85)”.
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[12] ETS 300 547 (1994): “European digital cellular telecommunications system(phase 2); Advice of Charge (AoC) supplementary services - Stage 2 (GSM03.86)”.
[13] ETS 300 548 (1994): “European digital cellular telecommunications system(Phase 2); Call Barring (CB) supplementary services - Stage 2 (GSM 03.88)”
[14] ETS 300 557 (1995): “European digital cellular telecommunications system(Phase 2); Mobile radio interface layer 3 specification (GSM 04.08)”
[15] ETS 300 582 (1994): “European digital cellular telecommunications system(Phase 2); General on Terminal Adaptation Functions (TAF) for Mobile Stations(MS) (GSM 07.01)”
[16] ETS 300 590 (1995): “European digital cellular telecommunications system(Phase 2); Mobile-services Switching Centre - Base Station System (MSC -BSS) interface Layer 3 specification (GSM 08.08)”
[17] ETS 300 599 Fourth Edition (1996): “European digital cellulartelecommunications system (Phase 2); Mobile Application Part (MAP)specification (GSM 09.02)”
[18] ETS 300 604 (1994): “European digital cellular telecommunications system(Phase 2); General requirements on interworking between the Public LandMobile Network (PLMN) and the Integrated Services Digital Network (ISDN) orPublic Switched Telephone Network (PSTN) (GSM 09.07)”
[19] ETS 300 607 (1994): “European digital cellular telecommunications system(Phase 2); Information element mapping between Mobile Station - Base StationSystem (MS - BSS) and Base Station System - Mobile-services SwitchingCentre (BSS - MSC) Signalling procedures and the Mobile Application Part(MAP) (GSM 09.10)”
[20] ETS 300 627 (1996): “European digital cellular telecommunications system(Phase 2); Subscriber and equipment trace (GSM 12.08)”
[21] ETS 300 356-1 (1995): “Integrated Services Digital Network (ISDN); SignallingSystem No. 7; ISDN User Part (ISUP) version 2 for the international interface;Part 1: Basic services”
[22] ITU-T Recommendation Q.850 (1996): “Usage of cause and location in theDigital Subscriber Signalling System No. 1 and the Signalling System No. 7ISDN User Part”
3 Definitions, symbols and abbreviations
3.1 Definitions
A subscriber: The calling mobile subscriber.
B subscriber: The mobile subscriber originally called by the A subscriber.
C subscriber: The subscriber to whom the B subscriber has requested that calls be forwarded. The Csubscriber may be fixed or mobile.
Location Information: Information to define the whereabouts of the MS, and the age of the informationdefining the whereabouts.
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3.2 Abbreviations
A&O Active & OperativeACM Address Complete MessageANM ANswer MessageAoC Advice of ChargeBC Bearer CapabilityBOIC-exHC&BOIZC Barring of Outgoing International Calls except those directed to the HPLMN
Country & Barring of Outgoing InterZonal CallsBOIZC Barring of Outgoing InterZonal CallsBOIZC-exHC Barring of Outgoing InterZonal Calls except those directed to the HPLMN
CountryCFB Call Forwarding on BusyCFNRc Call Forwarding on mobile subscriber Not ReachableCFNRy Call Forwarding on No ReplyCFU Call Forwarding UnconditionalCLIP Calling Line Identity PresentationCLIR Calling Line Identity RestrictionCOLP COnnected Line identity PresentationCOLR COnnected Line identity RestrictionCUG Closed User GroupCW Call WaitingFTN Forwarded-To NumberFTNW Forwarded-To NetWorkGMSCB Gateway MSC of the B subscriberHLC Higher Layer CompatibilityHLRB The HLR of the B subscriberHPLMNB The HPLMN of the B subscriberIAM Initial Address MessageIPLMN Interrogating PLMN - the PLMN containing GMSCBLLC Lower Layer CompatibilityMO Mobile OriginatedMPTY MultiParTYMT Mobile TerminatedNDUB Network Determined User BusyNRCT No Reply Call TimerPRN Provide Roaming NumberSIFIC Send Information For Incoming CallSIFOC Send Information For Outgoing CallSRI Send Routeing InformationUDUB User Determined User BusyVLRA The VLR of the A subscriberVLRB The VLR of the B subscriberVMSCA The Visited MSC of the A subscriberVMSCB The Visited MSC of the B subscriberVPLMNA The Visited PLMN of the A subscriberVPLMNB The Visited PLMN of the B subscriber
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4 Architecture
Subclauses 4.1 and 4.2 show the architecture for handling a basic MO call and a basic MT call. A basicmobile-to-mobile call is treated as the concatenation of an MO call and an MT call.
4.1 Architecture for an MO call
A basic mobile originated call involves signalling between the MS and its VMSC via the BSS, between theVMSC and the VLR and between the VMSC and the destination exchange, as indicated in figure 1.
MS
VMSCA
VLRAVPLMNA
Air I/F signalling
SIFOC/ack
IAM (ISUP)BSSA
'A' I/F signalling
Figure 1: Architecture for a basic mobile originated call
In figure 1 and throughout this specification, the term ISUP is used to denote the telephony signallingsystem used between exchanges. In a given network, any telephony signalling system may be used.
When the user of an MS wishes to originate a call, the MS establishes communication with the networkusing air interface signalling, and sends a message containing the address of the called party. VMSCArequests information to handle the outgoing call (SIFOC) from VLRA, over an internal interface of theMSC/VLR. If VLRA determines that the outgoing call is allowed, it responds with a SIFOC ack. VMSCA:
- establishes a traffic channel to the MS, and- constructs an ISUP IAM using the called party address and sends it to the destination exchange.
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4.2 Architecture for an MT call
A basic mobile terminated call involves signalling as indicated in figure 2. Communication betweenVMSCB and the MS is via the BSS, as for the mobile originated case. The IPLMN, containing GMSCB, isin principle distinct from HPLMNB, containing HLRB, but the practice for at least the majority of currentGSM networks is that a call to a GSM MS will be routed to a GMSC in HPLMNB.
IPLMN
GMSCB
VPLMNB
HLRB
HPLMNB
IAM(ISUP)
IAM(ISUP)
Send RouteingInfo/ack
Provide RoamingNumber/ack
Air I/Fsignalling
MS
VLRB
VMSCB
SIFICPage/ackComplete call
BSSB
'A' I/Fsignalling
Figure 2: Architecture for a basic mobile terminated call
When GMSCB receives an ISUP IAM, it requests routeing information from HLRB using the MAPprotocol. HLRB requests a roaming number from VLRB, also using the MAP protocol, and VLRB returns aroaming number in the Provide Roaming Number Ack. HLRB returns the roaming number to GMSCB inthe Send Routeing Info ack. GMSCB uses the roaming number to construct an ISUP IAM, which it sendsto VMSCB. When VMSCB receives the IAM, it requests information to handle the incoming call (SIFIC)from VLRB, over an internal interface of the MSC/VLR. If VLRB determines that the incoming call isallowed, it requests VMSCB to page the MS. VMSCB pages the MS using air interface signalling. Whenthe MS responds, VMSCB informs VLRB in the Page ack message. VLRB instructs VMSCB to connectthe call in the Complete call, and VMSCB establishes a traffic channel to the MS.
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5 Information flows
5.1 Information flow for an MO call
An example information flow for an MO call is shown in figure 3; many variations are possible. Signallingover the air interface between MSA and BSSA or VMSCA is shown by dotted lines; signalling over the ‘A’interface between BSSA and VMSCA is shown by dashed lines; signalling over the B interface betweenVMSCA and VLRA is shown by chain lines; and ISUP signalling between VMSCA and the destinationexchange is shown by solid lines.
MSA BSSA VMSCA VLRA
CM service req
Authenticate
Authenticate resp
Cipher mode cmd(note 3)
Cipher mode comp
Setup
Call proceeding
Assignment cmd
Assignment comp
Connect ack
CM service req
Authenticate
Authenticate ack
Start ciphering(note 3)
Cipher mode comp
Allocate channel
Allocation complete
Alert
Connect
Process access req
Authenticate(note 1)
Authenticate ack
Set cipher mode(note 2)
Process access req
SIFOC
Complete call
IAM
ACM
ANM
Authenticateaccept
ack
Figure 3: Information flow for a basic mobile originated call
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NOTE 1: Authentication may occur at any stage during the establishment of an MO call; itsposition in this message flow diagram is an example.
NOTE 2: Ciphering may be initiated at any stage after authentication; its position in thismessage flow diagram is an example.
NOTE 3: If ciphering is not required, the MSC may send a CM service accept towards the MS;optionally it may instead send a ‘start ciphering’ request indicating that no ciphering isrequired.
NOTE 4: The network may request the IMEI from the MS, and may check the IMEI, at any stageduring the establishment of an MO call, either as part of the procedure to startciphering or explicitly after ciphering has started; this is not shown in this message flowdiagram.
When the user wishes to originate a call, MSA establishes a signalling connection with BSSA, and sendsa Connection Management (CM) service request to BSSA, which relays it to VMSCA. VMSCA sends aProcess access request to VLRA. VLRA may then initiate authentication, as described in [3]. VLRA mayalso initiate ciphering at this stage, as described in [3].
If VLRA determines that MSA is allowed service, it sends a Process access request ack to VMSCA. IfVMSCA has received a Set cipher mode message from VLRA, the Process access request ack messagetriggers a Start ciphering command message towards BSSA; otherwise VMSCA sends a CM serviceaccept message towards BSSA.
If BSSA receives a Start ciphering command from VMSCA, it initiates ciphering as described in [3]; whenciphering is successfully initiated, MSA interprets this in the same way as a CM service accept. Ifciphering is not required at this stage, BSSA relays the CM service accept to MSA.
When MSA has received the CM service accept, or ciphering has been successfully initiated, MSA sendsa Setup message containing the B subscriber address via BSSA to VMSCA. MSA also uses the Setupmessage to indicate the bearer capability required for the call; VMSCA translates this bearer capability intoa GSM basic service, and determines whether an interworking function is required. VMSCA sends toVLRA a request for information to handle the outgoing call, using a Send Info For Outgoing Call (SIFOC)message containing the B subscriber address.
If VLRA determines that the call should be connected, it sends a Complete Call message to VMSCA.VMSCA sends a Call Proceeding message via BSSA to MSA, to indicate that the call request has beenaccepted, and sends an Allocate channel message to BSSA, to trigger BSSA and MSA to set up a trafficchannel over the air interface. The Call Proceeding message includes bearer capability information if anyof the negotiable parameters of the bearer capability has to be changed. When the traffic channelassignment process is complete (indicated by the Allocation complete message from BSSA to VMSCA),VMSCA constructs an ISUP IAM using the B subscriber address, and sends it to the destinationexchange.
When the destination exchange returns an ISUP Address Complete Message (ACM), VMSCA sends anAlert message via BSSA to MSA, to indicate to the calling user that the B subscriber is being alerted.
When the destination exchange returns an ISUP ANswer Message (ANM), VMSCA sends a Connectmessage via BSSA to MSA, to instruct MSA to connect the speech path.
The network then waits for the call to be cleared.
For an emergency call, a different CM service type (emergency call) is used, and the mobile may identifyitself by an IMEI. It is a network operator option whether to allow an emergency call when the mobileidentifies itself by an IMEI. Details of the handling are shown in clause 7.
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5.2 Information flow for retrieval of routeing information for an MT call
The information flow for retrieval of routeing information for an MT call is shown in figure 4. ISUPsignalling between the originating exchange and GMSCB, and between GMSCB and VMSCB is shown bysolid lines; signalling over the MAP interfaces between GMSCB and HLRB and between HLRB and VLRBis shown by chain lines.
GMSCB HLRB VLRB VMSCBIAM
SRIPRN
SRI ackPRN ack
IAM
Figure 4: Information flow for retrieval of routeing information for a basic mobile terminated call
When GMSCB receives an IAM, it analyses the called party address. If GMSCB can derive an HLRaddress from the B party address, it sends a request for routeing information (SRI) to HLRB. HLRB sendsa request for a roaming number (PRN) to VLRB. VLRB returns the roaming number in the PRN ack, andHLRB relays the roaming number to GMSCB in the SRI ack. GMSCB constructs an IAM using theroaming number, and sends it to VMSCB.
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5.3 Information flow for an MT call
An example information flow for an MT call is shown in figure 5; many variations are possible. ISUPsignalling between GMSCB and VMSCB is shown by solid lines; signalling over the B interface betweenVMSCB and VLRB is shown by chain lines; signalling over the ‘A’ interface between VMSCB and BSSB isshown by dashed lines; and signalling over the air interface between VMSCB or BSSB and MSB is shownby dotted lines.
GMSCB VLRB VMSCB BSSB MSBIAM
SIFIC
Page MSPage
Page
Chan req
Imm ass
Page respMS conn
estabProcessaccess req
Set ciphermode (note 1)
Process
access req ack Startciphering(note 2)
Complete call
Cipher mode
commandCipher mode
completeSetup
Call conf
Allocatechannel
Assignment
command
complete
AssignmentAllocationcomplete
AlertingACM
ANMConnect
Complete callConnect ack
ack
Figure 5: Information flow for a basic mobile terminated call
NOTE 1: Ciphering may be initiated at any stage after the network has accepted the pageresponse; its position in this message flow diagram is an example.
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NOTE 2: If ciphering is not required, the MSC may send a ‘start ciphering’ request indicating thatno ciphering is required.
NOTE 3: This message flow diagram assumes that the MS has already been authenticated onlocation registration. If this is not so (for the first MT call after VLR restoration), thenetwork may initiate authentication after the MS responds to paging.
NOTE 4: The network may request the IMEI from the MS, and may check the IMEI, at any stageafter the MS responds to paging, either as part of the procedure to start ciphering orexplicitly after ciphering has started; this is not shown in this message flow diagram.
When VMSCB receives an IAM from GMSCB it sends to VLRB a request for information to handle theincoming call, using a Send Info For Incoming Call (SIFIC) message containing the roaming numberreceived in the IAM.
If VLRB recognises the roaming number, and MSB is allowed service, it sends a request to VMSCB topage MSB. If a radio connection between the network and MSB is already established, VMSCB respondsimmediately to the page request. If no radio connection exists, VMSCB sends a page request to BSSB,and BSSB broadcasts the page on the paging channel.
If MSB detects the page, it sends a channel request to BSSB, which responds with an immediateassignment command, to instruct MSB to use the specified signalling channel. MSB then sends a pageresponse on the signalling channel; BSSB relays this to VMSCB. VMSCB sends a Process accessrequest message to VLRB to indicate that MSB has responded to paging. VLRB may then initiateauthentication, as described in [3]. VLRB may also initiate ciphering at this stage, as described in [3].
If VLRB determines that MSB is allowed service, it sends a Process access request ack to VMSCB. TheProcess access request ack message triggers a Start ciphering command message towards BSSB; ifVMSCB has not received a Set cipher mode message from VLRB, the Start ciphering command indicatesno ciphering.
VLRB then sends a Complete call message to VMSCB. VMSCB sends a Setup message towards MSB.The Setup message may include bearer capability information for the call.
When MSB receives the Setup message from BSSB, it responds with a Call confirmed message. The CallConfirmed message includes bearer capability information if any of the negotiable parameters of thebearer capability has to be changed. When VMSCB receives the Call confirmed message via BSSB, itsends an Allocate channel message to BSSB. BSSB instructs MSB to tune to a traffic channel by sendingan Assignment command. When MSB has tuned to the specified traffic channel it responds with anAssignment complete, message, which BSSB relays to VMSCB as an Allocation complete, and sends anAlerting message to indicate that the called user is being alerted. VMSCB sends an ACM to GMSCB,which relays it to the originating exchange.
When the called user answers, MSB sends a Connect message, which BSSB relays to VMSCB. VMSCB:
- responds with a Connect ack message towards MSB;- sends an ANM to GMSCB, which relays it to the originating exchange;- sends a Complete call ack to VLRB.
The network then waits for the call to be cleared.
Page 20GSM 03.18 Version 2.1.0: February 1997
6 Principles for interactions with supplementary services
This clause specifies the principles used to describe the invocation of the GSM supplementary serviceswhich were standardised when this specification was drafted. Registration, erasure, activation,deactivation and interrogation are call-independent operations; they are therefore outside the scope of thisspecification. Descriptions may be found in the stage 2 specifications for each supplementary service.
In the modelling used in this specification, each supplementary service which a network entity supports ismanaged by a supplementary service handler, which handles data in the entity in which it runs. The callhandling processes defined in this specification use the data to define the contents of messages to otherentities. The basic call handling processes defined in this specification interact with the supplementaryservice handlers as shown in the SDL diagrams and the supporting text. If a network entity does notsupport a supplementary service, it bypasses the interaction with the handler for that supplementaryservice. Exceptions to this general principle are described later in this clause.
6.1 Line identification services (GSM 03.81)
6.1.1 Calling Line Identification Presentation (CLIP)
The basic call handling processes ICH_VLR and ICH_MSC interact with the processes CLIP_MAF001and CLIP_MAF002 [7] as described in subclauses 7.3.2 and 7.3.1.
6.1.2 Calling Line Identification Restriction (CLIR)
The basic call handling processes OCH_MSC and OCH_VLR interact with the processes CLIR_MAF004and CLIR_MAF003 [7] as described in subclauses 7.1.1 and 7.1.2.
6.1.3 Connected Line Identification Presentation (COLP)
The basic call handling processes OCH_MSC and OCH_VLR interact with the processes COLP_MAF006and COLP_MAF005 [7] as described in subclauses 7.1.1 and 7.1.2.
The basic call handling processes MT_GMSC and ICH_MSC interact with the process COLP_MAF039 [7]as described in subclauses 7.2.1 and 7.3.1.
6.1.4 Connected Line Identification Restriction (COLR)
The basic call handling processes ICH_VLR and ICH_MSC interact with the processes COLR_MAF040and COLR_MAF041 [7] as described in subclauses 7.3.2 and 7.3.1.
6.2 Call forwarding services (GSM 03.82)
6.2.1 Call Forwarding Unconditional (CFU)
The basic call handling process SRI_HLR interacts with the process MAF007 [8] as described insubclause 7.2.2
6.2.2 Call Forwarding on mobile subscriber Busy (CFB)
The basic call handling process ICH_VLR interacts with the process MAF008 [8] as described insubclause 7.3.2
6.2.3 Call Forwarding on No Reply (CFNRy)
The basic call handling process ICH_VLR interacts with the process MAF009 [8] as described insubclause 7.3.2
6.2.4 Call Forwarding on mobile subscriber Not Reachable (CFNRc)
The basic call handling processes SRI_HLR and ICH_VLR interact with the process MAF010 [8] asdescribed in subclauses 7.2.2 and 7.3.2
Page 21GSM 03.18 Version 2.1.0: February 1997
6.3 Call wait (GSM 03.83)
The basic call handling process ICH_VLR interacts with the process MAF013 [9] as described insubclause 7.3.2. Further details of the handling of call waiting are given in subclauses 7.3.1 & 7.3.2.
6.4 Call hold (GSM 03.83)
Invocation of call hold before a basic call has been established will be rejected.
6.5 Multiparty (GSM 03.84)
Invocation of multiparty before a basic call has been established will be rejected.
6.6 Closed user group (GSM 03.85)
The basic call handling process OCH_VLR interacts with the process CUG_MAF014 [11] as described insubclause 7.1.2.
The basic call handling process SRI_HLR interacts with the process CUG_MAF015 [11] as described insubclause 7.2.2.
The interactions between call forwarding and CUG [11] are handled as described in subclause 7.2.2.6.
6.7 Advice of charge (GSM 03.86)
The interactions between Advice of Charge [12] and MO calls are handled as described in subclauses7.1.1 and 7.1.2.
The interactions between Advice of Charge [12] and MT calls are handled as described in subclauses7.3.1 and 7.3.2.
6.8 Call barring (GSM 03.88)
6.8.1 Barring of outgoing calls
The basic call handling process OCH_VLR interacts with the processes MAF017, MAF018 and MAF020[13] as described in subclause 7.1.2.
6.8.2 Barring of incoming calls
The basic call handling process SRI_HLR interacts with the processes MAF022 and MAF023 [13] asdescribed in subclause 7.2.2.
6.9 Explicit Call Transfer (GSM 03.91)
There is no interaction between Explicit Call Transfer and the basic call handling described in thisspecification.
Page 22GSM 03.18 Version 2.1.0: February 1997
7 Functional requirements of network entities
The text in this clause is a supplement to the definition in the SDL diagrams; it does not duplicate theinformation in the SDL diagrams.
The entities described in this clause interwork with other entities over three different types of interface:
- The A interface, used to interwork between the MSC and the BSS or the MS;- The C, D & F interfaces, used to interwork between the MSC & HLR (C), VLR & HLR (D) and MSC
& EIR (F);- Telephony signalling interfaces, used to interwork between an MSC and another exchange.
The protocols used over the A interface are BSSMAP, which is specified in [16], for interworking with theBSS and DTAP, which is specified in [14], for interworking with the MS.
The protocol used over the C, D & F interfaces is MAP, which is specified in [17].
For the purposes of this specification, the protocol used over telephony signalling interfaces is ISUP,which is specified in [21]; other telephony signalling systems may be used instead.
This specification shows the call handling application processes interworking with a protocol handler foreach of the protocols listed above. Each protocol defines supervision timers. If a supervision timer expiresbefore a distant entity responds to a signal, the handling is as defined in the appropriate protocolspecification. In general, the protocol handler reports timer expiry to the application as an error conditionor negative response. Where a timer is shown in this specification, therefore, it is an application timerrather than a protocol timer. Interworking with the protocol handlers uses functional signal names whichdo not necessarily have a one-to-one correspondence with the names of messages used in the protocols.
An MSC which receives an IAM from an originating exchange may react in three different ways:
- It acts as a transit exchange, i.e. it relays the IAM to a destination exchange determined by analysisof the called party address, and thereafter relays other telephony signalling between the originatingand destination exchange until the connection is released. This behaviour is not specific to GSM;
- It acts as a terminating exchange, i.e. it attempts to connect the call to an MS currently registered inthe service area of the MSC;
- It acts as a GMSC, i.e. it interrogates an HLR for information to route the call. If the HLR returnsrouteing information, the MSC uses the routeing information from the HLR to construct an IAM,which it sends to a destination exchange determined by analysis of the routeing information fromthe HLR.
Annex A describes the method which the MSC uses to decide how to process the IAM.
7.1 MO call
7.1.1 Functional requirements of serving MSC
7.1.1.1 Process OCH_MSC
Sheet 1: the MSC converts the GSM bearer capability negotiated between the MSC and the MS to a GSMbasic service according to the rules defined in [15].
Sheet 2, sheet 4: at any stage after the Setup has been received, the MS may terminate the transactionwith the network by sending a Release transaction request.
7.1.1.2 Procedure Process_Access_Request_MSC
Sheet 1, sheet 2: instead of using the explicit procedure Obtain_IMEI_MSC, the MSC may encapsulatethe request for the IMEI in the Start ciphering request; the BSS relays the response in the Cipher Modecomplete message to the MSC.
Sheet 2: the MSC maps the negative response received on the B interface to the appropriate reject causeaccording to the rules defined in [19].
Page 23GSM 03.18 Version 2.1.0: February 1997
Sheet 2: The Start ciphering request may indicate one of several ciphering algorithms, or no ciphering.
Sheet 2, sheet 3: At any stage, the MS may terminate the transaction with the network by sending a CMservice abort message.
Sheet 2, sheet 3: if the MSC receives a Setup message from the MS while the access request is beinghandled, the message is saved for processing after the access request has been handled.
7.1.1.3 Procedure Set_CLI_Presentation_Indicator_MSC
The MS may terminate the transaction with the network by sending a Release transactionmessage while aresponse is awaited from the process CLIR_MAF004. The message is saved for processing after returnfrom the procedure.
7.1.1.4 Procedure Set_COLP_Info_MSC
The MS may terminate the transaction with the network by sending a Release transactionmessage while aresponse is awaited from the process COLP_MAF006. The message is saved for processing after returnfrom the procedure.
7.1.1.5 Procedure Handle_AoC_MO_MSC
The charging parameters and the Boolean variable Acknowledgment required are global data which canbe read by the parent process.
7.1.1.6 Procedure Obtain_IMSI_MSC
The MS may terminate the transaction with the network while the MSC is waiting for the MS to return itsIMSI. If a CC connection has not been established, the MS uses CM Service Abort; otherwise it uses aRelease, Release Complete or Disconnect. The MSC aborts the transaction with the VLR and returns anaborted result to the parent process.
7.1.1.7 Procedure Authenticate_MSC
The MS may terminate the transaction with the network while the MSC is waiting for the MS to respond toan authentication request. If a CC connection has not been established, the MS uses CM Service Abort;otherwise it uses a Release, Release Complete or Disconnect. The MSC aborts the transaction with theVLR and returns an aborted result to the parent process.
7.1.1.8 Procedure Obtain_IMEI_MSC
The MS may terminate the transaction with the network while the MSC is waiting for the MS to return itsIMEI. If a CC connection has not been established, the MS uses CM Service Abort; otherwise it uses aRelease, Release Complete or Disconnect. The MSC aborts the transaction with the VLR and returns anaborted result to the parent process.
7.1.1.9 Procedure Check_IMEI_MSC
The MS may terminate the transaction with the network while the MSC is waiting for the MS to return itsIMEI. If a CC connection has not been established, the MS uses CM Service Abort; otherwise it uses aRelease, Release Complete or Disconnect. The MSC aborts the transaction with the VLR and returns anaborted result to the parent process.
The MS may terminate the transaction with the network while the MSC is waiting for the result of the IMEIcheck from the EIR. If a CC connection has not been established, the MS uses CM Service Abort;otherwise it uses a Release, Release Complete or Disconnect. The MSC aborts the transaction with theVLR and returns an aborted result to the parent process.
Page 24GSM 03.18 Version 2.1.0: February 1997
Process in the MSC tohandle an outgoing call request
Process OCH_MSC OCH_MSC1(4)
Signals to/from the leftare to/from the BSS;signals to/from the right are to/from the VLR.
Idle
CMservicerequest
Process_Access_
Request_MSC
Result=Pass?
Wait_For_Setup
Setup
Convert GSM BC to
basic service
Send Info ForOutgoing Call
Wait_For_MO_Call_
Result
CMServiceAbort
Releasecall
resources
Idle
Yes
No
Figure 6a: Process OCH_MSC (sheet 1)
Page 25GSM 03.18 Version 2.1.0: February 1997
Process in the MSC tohandle an outgoing call request
Process OCH_MSC OCH_MSC2(4)
Signals to/from the leftare to/from the BSS;signals to/from the right are to/from the VLRunless marked otherwise
Wait_For_MO_Call_
Result
Releasetransaction
Abort
ReleaseCall
Resources
Idle
CompleteCall
Convert GSM BC to channel
requirement
CallProceeding
Allocatechannel
Wait_For_Allocation_Complete
Release transaction
ReleaseCall
Resources
Idle
Allocation failure
Release transaction
Allocationcomplete
Set_CLI_Presentation_
Indicator_MSC
Result=call allowed?
InitialAddress
Towardsdestinationexchange
Wait_For_ACM
Send Info ForOutgoing Callnegative response
Releasetransaction
ReleaseCall
Resources
Idle
No
Yes
Figure 6b: Process OCH_MSC (sheet 2)
Page 26GSM 03.18 Version 2.1.0: February 1997
Process in the MSC tohandle an outgoing call request
Process OCH_MSC OCH_MSC3(4)
Signals to/from the leftare to/from the BSS;signals to/from the right are to/from the destination exchange.
Wait_For_ACM
AddressComplete
Alert
Wait_For_ANM
Answer
Set_COLP_Info_MSC
Handle_AoC_MO_MSC
Connect
Acknowledgmentrequired?
Wait_For_Connect_Ack
ConnectAck
Wait_For_Clear
Start AoCacknowledgment
timer
Wait_For_AoC_Ack
Connect
Wait_For_AoC_Ack
ChargingParametersack
Releasetransaction
Release
Releasecall
resources
Idle
ConnectAck
Releasetransaction
AoCacknowledgmenttimer expired
No
Yes
Figure 6c: Process OCH_MSC (sheet 3)
Page 27GSM 03.18 Version 2.1.0: February 1997
Process in the MSC tohandle an outgoing call request
Process OCH_MSC OCH_MSC4(4)
Signals to/from the leftare to/from the BSS;signals to/from the right are to/from the destination exchange
Wait_For_ACM,Wait_For_ANM,Wait_For_Connect_Ack,Wait_For_Clear
Releasetransaction
ReleaseTowardsdestinationexchange
Releasecall
resources
Idle
ReleaseFrom destinationexchange
Releasetransaction
Figure 6d: Process OCH_MSC (sheet 4)
Page 28GSM 03.18 Version 2.1.0: February 1997
Procedure in the MSCto handle a request from the MS for system access
Procedure Process_Access_Request_MSC PAR_MSC1(3)
Signals to/from the leftare to/from the BSS;signals to/from the right are to/from the VLR.
ProcessAccessRequest
Wait_For_PAR_Result
ProvideIMSI
Obtain_IMSI_MSC
Result=Pass?
Result:=Fail
Wait_For_PAR_Result
Authenticate
Authenticate_MSC
Result=Pass?
Result:=Fail
Wait_For_PAR_Result
TraceSubscriberActivity
Tracing Active:=TRUE
Wait_For_PAR_Result
Wait_For_PAR_Result
CMserviceabort
Abort
Result:=Fail
SetCipheringMode
CipheringRequired:=
TRUE
Wait_For_PAR_Result
No
Yes
No
Yes
Figure 7a: Procedure Process_Access_Request_MSC (sheet 1)
Page 29GSM 03.18 Version 2.1.0: February 1997
Procedure in the MSCto handle a request from the MS for system access
Procedure Process_Access_Request_MSC PAR_MSC2(3)
Signals to/from the leftare to/from the BSS;signals to/from the right are to/from the VLR.
Wait_For_PAR_Result
Abort
CM Service type=Page Response?
Map negative response toreject cause
CM ServiceReject
Result:=Fail
Releasetransaction
Process AccessRequest negative response
ProcessAccessRequest ack
Cipheringrequired?
CM Service type=Page Response?
Wait_For_TMSI_
Reallocation
CMserviceabort
Abort
Result:=Fail
ProvideIMEI
Obtain_IMEI_MSC
Result=Pass?
Result:=Fail
Wait_For_TMSI_
Reallocation
Setup CheckIMEI
Check_IMEI_MSC
Result=Pass?
Wait_For_TMSI_
Reallocation
Abort
Map negative response toreject cause
CM ServiceReject
Result:=Fail
ForwardNew TMSI
ReallocateTMSI
Wait_For_TMSI_Ack
UseExistingTMSI
Result:=Pass
CM ServiceAccept
Startciphering
No
No
No
Yes
No
Yes
No
Yes
Yes
Figure 7b: Procedure Process_Access_Request_MSC (sheet 2)
Page 30GSM 03.18 Version 2.1.0: February 1997
Procedure in the MSCto handle a request from the MS for system access
Procedure Process_Access_Request_MSC PAR_MSC3(3)
Signals to/from the leftare to/from the BSS;signals to/from the right are to/from the VLR.
Wait_For_TMSI_Ack
CMserviceabort
Abort
Result:=Fail
Setup Abort
Result:=Fail
TMSIReallocationFailure
ForwardNew TMSInegative response
Result:=Pass
TMSIReallocationComplete
ForwardNew TMSI ack
Figure 7c: Procedure Process_Access_Request_MSC (sheet 3)
Page 31GSM 03.18 Version 2.1.0: February 1997
Procedure in the MSCto determine the CLI presentation indicator value
Procedure Set_CLI_Presentation_Indicator_MSC CAIND_M1(1)
Signals to/from the rightare to/from the process CLIR_MAF004 Initiate
handlingof CLIR
Wait_For_CLIR_Info
Releasetransaction
From BSS Clearcall
Result:=Call notallowed
Continuecallhandling
Result:=Call
allowed
Figure 8: Procedure Set_CLI_Presentation_Indicator_MSC
Page 32GSM 03.18 Version 2.1.0: February 1997
Procedure in the MSCto determine the COLPinformation to be sent to the MS
Procedure Set_COLP_Info_MSC COINF_M1(1)
Signals to/from the rightare to/from the processCOLP_MAF006 Initiate
handlingof COLP
Wait_For_COLP_Info
Releasetransaction
From BSSContinuecallhandling
ReleaseFrom destinationexchange
Figure 9: Procedure Set_COLP_Info_MSC
Page 33GSM 03.18 Version 2.1.0: February 1997
Procedure in the MSCto handle AoC signalling towards the MS for an MO call
Procedure Handle_AoC_MO_MSC AoCMO_M1(1)
AoC(I)provisioned?
AoC(C)provisioned?
Acknowledgmentrequired:=
False
Setcharging
parameters
Acknowledgmentrequired:=
True
Setcharging
parameters
No
No
Yes
Yes
Figure 10: Procedure Handle_AoC_MO_MSC
Page 34GSM 03.18 Version 2.1.0: February 1997
Procedure in the MSCto obtain the IMSI from the MSand relay it to the VLR
Procedure Obtain_IMSI_MSC OIMSI_M1(1)
Signals to/from the left are to/from the BSS;Signals to/from the rightare to/from the VLR Send
IMSI
Wait_For_IMSI
Send IMSIack
ProvideIMSI ack
Result:=Pass
Releasetransaction
Abort
Result:=Aborted
Send IMSInegativeresponse
Releasetransaction
Figure 11: Procedure Obtain_IMSI_MSC
Page 35GSM 03.18 Version 2.1.0: February 1997
Procedure in the MSCto obtain the IMSI from the MSand relay it to the VLR
Procedure Authenticate_MSC AUT_MSC1(1)
Signals to/from the left are to/from the BSS;Signals to/from the rightare to/from the VLR Authenticate
Wait_For_Auth_Response
Authenticateack
Authenticateack
Wait_For_Auth_Result
Authenticationaccepted
Result:=Pass
Authenticationrejected
Authenticationrejected
Releasetransaction
Abort
Result:=Aborted
Authenticatenegativeresponse
Releasetransaction
Figure 12: Procedure Authenticate_MSC
Page 36GSM 03.18 Version 2.1.0: February 1997
Procedure in the MSCto obtain the IMEI from the MSand relay it to the VLR
Procedure Obtain_IMEI_MSC OIMEI_M1(1)
Signals to/from the left are to/from the BSS;Signals to/from the rightare to/from the VLR Send
IMEI
Wait_For_IMEI
Send IMEIack
ProvideIMEI ack
Result:=Pass
Releasetransaction
Abort
Result:=Aborted
Send IMEInegativeresponse
Releasetransaction
Figure 13: Procedure Obtain_IMEI_MSC
Page 37GSM 03.18 Version 2.1.0: February 1997
Procedure in the MSC to check theIMEI and relay the result to the VLR
Procedure Check_IMEI_MSC CIMEI_M1(1)
Signals to/from the leftare to/from the BSS;signals to/from the right are to/from the VLR unless marked otherwise.
IMEIavailable?
Send IMEI
Wait_For_IMEI
CMserviceabort
Abort
Result:=Aborted
Send IMEInegativeresponse
Releasetransaction
Send IMEIack
Check IMEI To EIR
Wait_for_Check_IMEI_
Result
Releasetransaction
Abort
Result:=Aborted
Check IMEInegative response
From EIR
Check IMEInegative response
Result:=Pass
Check IMEIack
From EIR
Check IMEIack
No
Yes
Figure 14: Procedure Check_IMEI_MSC
Page 38GSM 03.18 Version 2.1.0: February 1997
7.1.2 Functional requirements of VLR
7.1.2.1 Process OCH_VLR
Sheet 2: it is an implementation option to carry out the check for operator determined barring of alloutgoing calls before the check on provisioning of the requested basic service.
Sheet 2: the negative response ‘call barred’ indicates whether the reason is operator determined barringor supplementary service barring, according to the result returned by the procedure Check_OG_Barring.
7.1.2.2 Procedure Process_Access_Request_VLR
Sheet 1: it is a network operator decision (subject to MoU requirements) how often an MS should beauthenticated.
Sheet 2: the processes Update_Location_VLR and Subscriber_Present_VLR are described in [17].
Sheet 2: it is a network operator decision (subject to MoU requirements) whether a connection should beciphered.
Sheet 3: it is a network operator decision (subject to MoU requirements) how often an IMEI should bechecked.
Sheet 5: it is a network operator decision whether emergency calls are allowed from an ME with no SIM.
7.1.2.3 Procedure Check_BAOC
Sheet 1: if the VLR receives an Abort message from the MSC while it is awaiting a response from theprocess MAF017, the message is saved for handling after return from the procedure.
7.1.2.4 Procedure OG_CUG_Check
If the VLR receives an Abort message from the MSC while it is awaiting a response from the processMAF014, the message is saved for handling after return from the procedure.
7.1.2.5 Procedure Check_OG_Barring
Sheet 2: if the VLR receives an Abort message from the MSC while it is awaiting a response from theprocess MAF018 or MAF019, the message is saved for handling after return from the procedure.
7.1.2.6 Procedure Get_LI_Subscription_Info_MO_VLR
If the VLR receives an Abort message from the MSC while it is awaiting a response from the processCLIR_MAF0003 or CLIR_MAF005, the message is saved for handling after return from the procedure.
7.1.2.7 Procedure Get_AoC_Subscription_Info_VLR
The indicator of whether or not AoC is provisioned is global data which can be read by the parent process.
7.1.2.8 Procedure Obtain_Identity_VLR
It is a network operator decision whether open (unciphered) identification of the MS by its IMSI is allowed.
7.1.2.9 Procedure Obtain_IMSI_VLR
7.1.2.10 Procedure Authenticate_VLR
Sheet 1: the number of unused authentication sets which triggers the VLR to request furtherauthentication sets from the HLR is an operator option.
Page 39GSM 03.18 Version 2.1.0: February 1997
7.1.2.11 Procedure Obtain_Authentication_Sets_VLR
7.1.2.12 Procedure Start_Tracing_VLR
7.1.2.13 Procedure Check_IMEI _VLR
If the response from the EIR to a request to check an IMEI is:
- blacklisted, then service is not granted;- greylisted, then service is granted, but the network operator may decide to initiate tracing;- whitelisted, then service is granted.
7.1.2.14 Procedure Obtain_IMEI _VLR
7.1.2.15 Process Fetch_Authentication_Sets_VLR
Page 40GSM 03.18 Version 2.1.0: February 1997
Process in the VLR to handle an outgoing (MO) call setup request
Process OCH_VLR OCH_VLR1(2)
Signals to/from the leftare to/from the MSC.
Idle
ProcessAccessRequest
Process_Access_
Request_VLR
Result=Pass
Wait_For_SIFOC Idle
Yes
No
Figure 15a: Process OCH_VLR (sheet 1)
Page 41GSM 03.18 Version 2.1.0: February 1997
Process in the VLR to handle an outgoing (MO) call setup request
Process OCH_VLR OCH_VLR2(2)
Signals to/from the leftare to/from the MSC.
Wait_For_SIFOC
Send Info For Outgoing Call
Emergencycall?
Basicservice
provisioned?
Check_BAOC
Callbarred?
OG_CUG_Check
Callallowed?
Check_OG_Barring
Callbarred?
Get_LI_Subscription_Info_MO_VLR
Get_AoC_Subscription_
Info_VLR
CompleteCall
Idle
Set negativeresponse:Call barred
Send Info For Outgoing Call negativeresponse
Idle
Set negativeresponse:
CUG reject
Set negativeresponse:Call barred
Set negativeresponse:
Basic servicenot provisioned
Bearer service or teleservice
Abort
Idle
No
Yes
No
Yes
No
Yes
No
Yes
No
Yes
Figure 15b: Process OCH_VLR (sheet 2)
Page 42GSM 03.18 Version 2.1.0: February 1997
Procedure in the VLRto handle a request from the MS for system access
Procedure Process_Access_Request_VLR PAR_VLR1(5)
Identityknown?
Obtain_Identity_VLR
Result=Pass?
Identity=IMEI?
Authenticationrequired?
IMSIdetached:=
False
Confirmed byRadio Contact:=
True
1
Authenticate_VLR
Result=Pass?
2
Set negativeresponse:SystemFailure
3
Result=Fail?
Set negativeresponse:
UnidentifiedSubscriber
3
Result:=Aborted
6
No
Yes
No
No
Yes
Yes
No
Yes
No
Yes
No
Yes
Figure 16a: Procedure Process_Access_Request_VLR (sheet 1)
Page 43GSM 03.18 Version 2.1.0: February 1997
Procedure in the VLRto handle a request from the MS for system access
Procedure Process_Access_Request_VLR PAR_VLR2(5)
1
Location infoconfirmed in HLR
Update_Location_VLR
Mobile NotReachable Flag set?
Subscriber_Present_VLR
Data confirmed by HLR
Set negativeresponse:
UnidentifiedSubscriber
3
Roaming allowedin current LA?
Set negativeresponse:Roaming
Not Allowed
Tracingrequired?
Start_Tracing_VLR
Cipheringrequired?
4 5
False
Yes
False
True
No
Yes
Yes
Yes
No
No
No
True
Figure 16b: Procedure Process_Access_Request_VLR (sheet 2)
Page 44GSM 03.18 Version 2.1.0: February 1997
Procedure in the VLRto handle a request from the MS for system access
Procedure Process_Access_Request_VLR PAR_VLR3(5)
Signals to the leftare to the MSC.
4
SetCipheringMode
Identity:=IMSI
ProcessAccessRequest ack
IMEI checkrequired?
Check_IMEI_VLR
Result=Pass?
TMSIreallocationrequired?
ForwardNew TMSI
FreezeexistingTMSI
Wait_For_TMSI_Ack
UseExistingTMSI
Result:=Pass
Result=Fail?
IMSIdetached:=
True
Set negativeresponse:
IllegalEquipment
3
Result:=Aborted
5
Yes
Yes
Yes
No
No
Yes
No
No
Figure 16c: Procedure Process_Access_Request_VLR (sheet 3)
Page 45GSM 03.18 Version 2.1.0: February 1997
Procedure in the VLRto handle a request from the MS for system access
Procedure Process_Access_Request_VLR PAR_VLR4(5)
Signals from the leftare from the MSC.
2
Result=Aborted?
Result:=Aborted
Result=Procedure
Error?
Set negativeresponse:SystemFailure
3
Result=Unknown
Subscriber?
Result=UnidentifiedSubscriber?
Set negativeresponse:
UnidentifiedSubscriber
Set negativeresponse:
IllegalSubscriber
Wait_For_TMSI_Ack
ForwardNew TMSIack
UnfreezeexistingTMSI
Result:=Pass
ForwardNew TMSInegativeresponse
Yes
No
Yes
No
No
Yes
No
Yes
Figure 16d: Procedure Process_Access_Request_VLR (sheet 4)
Page 46GSM 03.18 Version 2.1.0: February 1997
Procedure in the VLRto handle a request from the MS for system access
Procedure Process_Access_Request_VLR PAR_VLR5(5)
Signals to the leftare to the MSC.
3
CM service type=Emergency call?
Emergency callsetup allowedwithout SIM?
IMEIrequired?
Obtain_IMEI_VLR
Result=Pass?
Identity:=IMEI
ProcessAccessRequest ack
Result:=Pass
Result=Fail?
Process AccessRequest negative response
Result:=Fail
Result:=Aborted
Yes
Yes
Yes
Yes
No
Yes
No
No
No
No
Figure 16e: Procedure Process_Access_Request_VLR (sheet 5)
Page 47GSM 03.18 Version 2.1.0: February 1997
Procedure to check callrequest against ODBAOCand SS BAOC
Procedure Check_BAOC CBAOC1(1)
Signals to/from the right are to/from the processMAF017
Operator determined BAOCimposed?
Result:=Call barred
(ODB)
Initiatehandlingof BAOC
Wait_For_BAOC_
Response
AbortContinuecallhandling
Callbarred?
Result:=Call barred(SS barring)
Result:=Call allowed
From MSC
Yes
No
Yes
No
Figure 17: Procedure Check_BAOC
Page 48GSM 03.18 Version 2.1.0: February 1997
Procedure to carry outCUG authorisation checkfor an outgoing (MO) call
Procedure OG_CUG_Check OG_CUG1(1)
Signals to/from the rightare to/from the processCUG_MAF014 outgoing
callrequest
Wait_For_CUG_Response
Abortrejectcall(cause)
Result:=Call barred
complete call(conditionalCUG info)
Result:=Call allowed
responseto callrequest
From MSC
Figure 18: Procedure OG_CUG_Check
Page 49GSM 03.18 Version 2.1.0: February 1997
Procedure to check callrequest against SS barringand ODB categories
Procedure Check_OG_Barring COB1(3)
Operator determinedBOIC imposed?
Destination address CC=Local CC?
1
Operator determinedBOIC-exHC imposed?
Destination address CC=Local CC?
1
Destination address CC=HPLMN CC?
1
Operator determinedBOIZC imposed?
Destination address ZC=Local ZC?
1
Operator determinedBOIZC-exHC imposed?
Destination address ZC=Local ZC?
1
Destination address CC=HPLMN CC?
Result:=Call barred
(ODB)
1
Yes
No
Yes
No
Yes
NoYes
No
Yes
No
Yes
No
Yes
No
Yes
NoYes
No
No
Yes
Figure 19a: Procedure Check_OG_Barring (sheet 1)
Page 50GSM 03.18 Version 2.1.0: February 1997
Procedure to check callrequest against SS barringand ODB categories
Procedure Check_OG_Barring COB2(3)
1
Operator determinedBOIC-exHC&BOIZCimposed?
2
Destination address ZC=Local ZC?
Destination address CC=Local CC?
2
Destination address CC=HPLMN CC?
Result:=Call barred
(ODB)
2
No
Yes
No
Yes
No
No
Yes
Yes
Figure 19b: Procedure Check_OG_Barring (sheet 2)
Page 51GSM 03.18 Version 2.1.0: February 1997
Procedure to check callrequest against SS barringand ODB categories
Procedure Check_OG_Barring COB3(3)2
Callbarred?
Initiatehandling of BOIC
To process MAF018
Wait_For_BOIC_
Response
AbortContinuecallhandling
From process MAF018
Callbarred?
Initiatehandling of BOIC-exHC
To process MAF020
Wait_For_BOIC-exHC_
Response
AbortContinuecallhandling
From process MAF020
Callbarred?
Result:=Call barred(SS barring)
Result:=Call allowed
From MSC
From MSC
No
No
Yes
No
Yes
Yes
Figure 19c: Procedure Check_OG_Barring (sheet 3)
Page 52GSM 03.18 Version 2.1.0: February 1997
Procedure in the VLRto retrieve subscription information for the CLIR & COLP line identificationservices for an MO call
Procedure Get_LI_Subscription_Info_MO_VLR GLI_MOV1(1)
Initiatehandling of CLIR
Wait_For_CLIR_Info
AbortContinuecallhandling
Initiatehandling of COLP
Wait_For_COLP_Info
AbortContinuecallhandling
From process COLP_MAF005
To process COLP_MAF005
From process CLIR_MAF003
To process CLIR_MAF003
From MSC
From MSC
Figure 20: Procedure Get_LI_Subscription_Info_MO_VLR
Page 53GSM 03.18 Version 2.1.0: February 1997
Procedure in the VLR to determine the subscriptionto Advice of Charge services
Procedure Get_AoC_Subscription_Info_VLR GAOCI_V1(1)
AoC(I)provisioned?
AoC(C)provisioned?
Set indicator:AoC not
provisioned
Set indicator:AoC(C)
provisioned
Set indicator:AoC(I)
provisioned
No
No
Yes
Yes
Figure 21: Procedure Get_AoC_Subscription_Info_VLR
Page 54GSM 03.18 Version 2.1.0: February 1997
Procedure in the VLRto obtain the identity of an MS
Procedure Obtain_Identity_VLR OID_VLR1(1)
Identity=IMSI?
Identificationallowed?
Obtain_IMSI_VLR
Result=Pass?
IMSIknown?
Result:=Fail
Result:=Pass
Result:=Aborted
No
Yes
Yes
No
Yes
No
No
Yes
Figure 22: Procedure Obtain_Identity_VLR
Page 55GSM 03.18 Version 2.1.0: February 1997
Process in the VLRto obtain the IMSI from the MS via the MSC
Procedure Obtain_IMSI_VLR OIMSI_V1(1)
Signals to/from the leftare to/from the MSC.
ProvideIMSI
Wait_For_IMSI
Abort
Result:=Aborted
ProvideIMSI ack
Result:=Pass
Figure 23: Procedure Obtain_IMSI_VLR
Page 56GSM 03.18 Version 2.1.0: February 1997
Procedure in the VLRto authenticate an MSvia the MSC
Procedure Authenticate_VLR AUT_VLR1(2)
Signals to/from the leftare to/from the MSC.
Authenticationsets available?
Obtain_Authentication_
Sets_VLR
Result=Pass?
Result=Aborted?
Result:=Aborted
Result=Procedure
Error?
Result:=Procedure
Error
Result:=Unknown
Subscriber
Authenticate
Wait_For_Authenticate_
Result
Authenticateack
Received SRES=expected SRES?
Moreauthenticationsets needed?
Fetch_Authentication_
Sets_VLR
Authenticationaccepted
Result:=Pass
1
Abort
Moreauthenticationsets needed?
Fetch_Authentication_
Sets_VLR
Result:=Aborted
2
No
No
Yes
No
Yes
No
Yes
Yes
Yes
No
No
Yes
No
Yes
Figure 24a: Procedure Authenticate_VLR (sheet 1)
Page 57GSM 03.18 Version 2.1.0: February 1997
Procedure in the VLRto authenticate an MSvia the MSC
Procedure Authenticate_VLR AUT_VLR2(2)
Signals to the leftare to the MSC.
1
Identity=IMSI?
Retrywith
IMSI?
Obtain_IMSI_VLR
Result=Pass?
IMSIknown?
IMSImatchesTMSI?
Authenticationrejected
Result:=Illegal
Subscriber
Identity:=IMSI
2
Authenticationaccepted
Result:=UnidentifiedSubscriber
Result:=Aborted
No
Yes
Yes
Yes
Yes
No
No
No
No
Yes
Figure 24b: Procedure Authenticate_VLR (sheet 2)
Page 58GSM 03.18 Version 2.1.0: February 1997
Procedure in the VLRto obtain authentication sets from the HLR
Procedure Obtain_Authentication_Sets_VLR OAS_VLR1(2)
Signals to/from the rightare to/from the HLR
SendAuthenticationInfo
Wait_For_Authentication_
Sets
SendAuthenticationInfo ack
Emptyresult?
Authenticationsets availablein VLR?
Re-useold
sets?
Result:=Pass
Result:=Procedure
Error
SendAuthenticationInfo negativeresponse
UnknownSubscriber?
Result:=Unknown
Subscriber
Yes
Yes
Yes No
No
No
No
Yes
Figure 25a: Procedure Obtain_Authentication_Sets_VLR (sheet 1)
Page 59GSM 03.18 Version 2.1.0: February 1997
Procedure in the VLRto obtain authentication sets from the HLR
Procedure Obtain_Authentication_Sets_VLR OAS_VLR2(2)
Signals to/from the left are to/from the MSC;Signals to/from the rightare to/from the HLR
Wait_For_Authentication_
Sets
Abort
Abort
Result:=Aborted
Abort
Authenticationsets available?
Re-useold
sets?
Result:=Pass
Result:=Procedure
Error
Yes
Yes No
No
Figure 25b: Procedure Obtain_Authentication_Sets_VLR (sheet 2)
Page 60GSM 03.18 Version 2.1.0: February 1997
Procedure in the VLRto request the MSC tostart activity tracing
Procedure Start_Tracing_VLR ST_TR_V1(1)
Signals to the left are to the MSC.
Tracingactive?
TraceSubscriberActivity
No
Yes
Figure 26: Procedure Start_Tracing_VLR
Page 61GSM 03.18 Version 2.1.0: February 1997
Procedure in the VLRto request the MSC tocheck an IMEI
Procedure Check_IMEI_VLR CIMEI_V1(1)
Signals to/from the leftare to/from the MSC
CheckIMEI
Wait_For_Check_IMEI_
Result
CheckIMEI ack
Servicegranted?
Result:=Fail
Result:=Pass
CheckIMEI negativeresponse
Abort
Result:=Aborted
No
Yes
Figure 27: Procedure Check_IMEI_VLR
Page 62GSM 03.18 Version 2.1.0: February 1997
Process in the VLRto obtain the IMSI from the MS via the MSC
Procedure Obtain_IMEI_VLR OIMEI_V1(1)
Signals to/from the leftare to/from the MSC
ProvideIMEI
Wait_For_IMEI
Abort
Result:=Aborted
ProvideIMEI ack
Result:=Pass
Figure 28: Procedure Obtain_IMEI _VLR
Page 63GSM 03.18 Version 2.1.0: February 1997
Process in the VLRto retrieve authenticationsets from the HLR
Process Fetch_Authentication_Sets_VLR FAS_VLR1(1)
Obiain_Authentication_
Sets_VLR
Figure 29: Process Fetch_Authentication_Sets_VLR
Page 64GSM 03.18 Version 2.1.0: February 1997
7.2 Retrieval of routeing information for MT call
7.2.1 Functional requirements of GMSC
7.2.1.1 Process MT_GMSC
Sheet 1: the suggested mapping from values of the Send Routeing Info negative response informationelement to values of the ISUP release cause (see [22]) is shown in table 1. The mapping used is a matterfor the network operator, depending on the telephony signalling system used.
Sheet 3: after the GMSC has sent an IAM to the destination VMSC or the forwarded-to exchange, it actsas a transparent relay for messages received from the originating exchange and the destination VMSC orthe forwarded-to exchange. Any message other than Address Complete, Connect, Answer or Releasecauses no change of state in the process MT_GMSC.
Table 1: Suggested mapping of Send Routeing Info (SRI) negative responses to ISUP releasecauses
SRI negative response ISUP release cause number ISUP release cause nameAbsent subscriber 20 Subscriber absentBearer service notprovisioned
57 Bearer capability not authorised
Call barred (ODB) 21 Call rejectedCall barred (SS barring) 21 Call rejectedCUG reject (Called party SSinteraction violation)
21 Call rejected
CUG reject (Incoming callsbarred within CUG)
55 Incoming calls barred within CUG
CUG reject (Subscriber notmember of CUG)
87 User not member of CUG
CUG reject (Requested basicservice violates CUGconstraints)
87 User not member of CUG
Data missing 111 Protocol error, unspecifiedFacility not supported 69 Requested facility not implementedForwarding violation 21 Call rejectedNumber changed 22 Number changedSystem failure 111 Protocol error, unspecifiedTeleservice not provisioned 57 Bearer capability not authorisedUnexpected data value 111 Protocol error, unspecifiedUnknown subscriber 1 Unallocated (unassigned) number
7.2.1.2 Procedure Handle_COLP_Forwarding_Interaction_MSC
The originating exchange or the destination exchange may release the call while a response is awaitedfrom the process COLP_MAF039. The message is saved for processing after return from the procedure.
Page 65GSM 03.18 Version 2.1.0: February 1997
Process in the GMSC tohandle a mobile-terminated call request
Process MT_GMSC MT_GMSC1(3)
Signals to/from the leftare to/from the originating exchange;signals to/from the rightare to/from the HLRunless otherwise marked
Idle
InitialAddress
From originatingexchange
SendRouteingInfo
Wait_For_Routeing_
Info
Release
Release callresources
Idle
SendRouteingInfo negativeresponse
Setcause
Release
SendRouteingInfo ack
Forwardingindicationreceived?
ConstructInitial
AddressMessage
InitialAddress
Towardsdestination MSC
Wait_For_ACM
Setredirectioninformation
InitialAddress
Towards destinationexchange
Wait_For_Forward_ACM
No
Yes
Figure 30a: Process MT_GMSC (sheet 1)
Page 66GSM 03.18 Version 2.1.0: February 1997
Process in the GMSC tohandle a mobile-terminated call request
Process MT_GMSC MT_GMSC2(3)
Signals to/from the left are to/from the originating exchange;signals to/from the right are to/from the destination exchange
Wait_For_ACM
AddressComplete
AddressComplete
Wait_For_Answer
Answer
Answer
Wait_For_Clear
Connect
Connect
Wait_For_Forward_ACM
AddressComplete
AddressComplete
Wait_For_Forward_Answer
Answer
Handle_COLP_Forwarding_
Interaction_MSC
Set COLPpresentation
indicator
Answer
Wait_For_Clear
Connect
Handle_COLP_Forwarding_
Interaction_MSC
Set COLPpresentation
indicator
Connect
Figure 30b: Process MT_GMSC (sheet 2)
Page 67GSM 03.18 Version 2.1.0: February 1997
Process in the GMSC tohandle a mobile-terminated call request
Process MT_GMSC MT_GMSC3(3)
Signals to/from the left are to/from the originating exchange;signals to/from the right are to/from the destination exchange
Wait_For_ACM,Wait_For_Forward_ACM,Wait_For_Answer,Wait_For_Forward_Answer,Wait_For_Clear
Release
Release
Release callresources
Idle
Release
Release
Wait_For_ACM,Wait_For_Forward_ACM,Wait_For_Answer,Wait_For_Forward_Answer,Wait_For_Clear
*
-
-
*
-
Figure 30c: Process MT_GMSC (sheet 3)
Page 68GSM 03.18 Version 2.1.0: February 1997
Procedure in the GMSC or VMSCto handle the interaction betweenCOLP and Call Forwarding
Procedure Handle_COLP_Forwarding_Interaction_MSC COINT_M1(1)
Signals to/from the rightare to/from the processCOLP_MAF039 initiate
handlingof COLP
Wait_For_COLP_Info
Release From originating exchange or destination exchange
continuecallhandling
Figure 31: Procedure Handle_COLP_Forwarding_Interaction_MSC
Page 69GSM 03.18 Version 2.1.0: February 1997
7.2.2 Functional requirements of HLR
7.2.2.1 Process SRI_HLR
Sheet 1: The procedures Check_Parameters, Subscription_Check_HLR and First_Forwarding_HLR canset the negative response parameter which is used by the process SRI_HLR to construct the SendRouteing Info negative response message. This negative response parameter is global data, accessibleby the process SRI_HLR.
Sheet 2: The procedure PRN_Error_HLR can set the negative response parameter which is used by theprocess SRI_HLR to construct the Send Routeing Info negative response message. This negativeresponse parameter is global data, accessible by the process SRI_HLR.
7.2.2.2 Procedure Check_Parameters
If any parameters required by the rules in clause 8 are missing from the message, the procedure sets thenegative response to ‘Data missing. If any parameter has a value which is not in the set of valuesexpected for the parameter, the procedure sets the negative response to ‘Unexpected data value’.
7.2.2.3 Procedure Subscription_Check_HLR
It is an implementation option to carry out the check for operator determined barring of incoming callsbefore the check on provisioning of the requested basic service.
The negative response ‘Call barred’ indicates whether the reason is operator determined barring orsupplementary service barring, according to the result returned by the procedure Check_IC_Barring.
The negative response ‘CUG reject’ indicates whether the reason is:
- Incoming calls barred within CUG;- Requested basic service violates CUG constraints;- Subscriber not member of CUG
according to the cause returned by the procedure IC_CUG_Check.
7.2.2.4 Procedure First_Forwarding_HLR
7.2.2.5 Procedure PRN_Error_HLR
7.2.2.6 Procedure Forward_CUG_Check
7.2.2.7 Procedure Derive_Requested_Basic_Service_HLR
The rules for deriving a GSM bearer capability from ISDN compatibility information or the MSISDN of theB subscriber are specified in [18]. If a GSM bearer capability cannot be derived from the ISDNcompatibility information or the MSISDN of the B subscriber, the HLR applies a default basic serviceaccording to the requirements of the operator.
7.2.2.8 Procedure Check_IC_Barring
7.2.2.9 Procedure IC_CUG_Check
7.2.2.10 Procedure Handle_CFU
The test ‘Normal call’ refers to the value of the indicator returned by the process MAF007.
7.2.2.11 Procedure Handle_CFNRc
The test ‘Mobile subscriber not reachable’ refers to the value of the indicator returned by the processMAF010.
Page 70GSM 03.18 Version 2.1.0: February 1997
Process in the HLR to handle a request for routeing information
Process SRI_HLR SRI_HLR1(2)
Signals to/from the leftare to/from the GMSC;signals to/from the rightare to/from the VLR
Idle
SendRouteingInfo
Check_Parameters
Result=Pass?
Subscription_Check_HLR
Result=Fail?
First_Forwarding_
HLR
Result=Fail?
Result=Forward?
GSM BC=NULL?
SetGSM BC
parameter
ProvideRoamingNumber
Wait_For_MSRN
2 1
Yes
No
No
No
No
Yes
Yes
Yes
Yes
No
Figure 32a: Process SRI_HLR (sheet 1)
Page 71GSM 03.18 Version 2.1.0: February 1997
Process in the HLR to handle a request for routeing information
Process SRI_HLR SRI_HLR2(2)
Signals to/from the leftare to/from the GMSC;signals to/from the rightare to/from the VLR
Wait_For_MSRN
ProvideRoamingNumber ack
Routeingaddress:=
MSRN
SendRouteingInfo ack
Idle
Provide RoamingNumber negativeresponse
PRN_Error_HLR
Result=Fail?
Send RouteingInfo negativeresponse
Idle
Forward_CUG_Check
Callallowed?
Routeingaddress:=
FTN
SendRouteingInfo ack
Idle
Set negativeresponse:
CUG reject
Called party SSinteractionviolation
1
2
Yes
No
Yes
No
Figure 32b: Process SRI_HLR (sheet 2)
Page 72GSM 03.18 Version 2.1.0: February 1997
Procedure to checkthe parameters of areceived message
Procedure Check_Parameters Chk_Par1(1)
All requiredparameters present?
All parameter values acceptable?
Set negativeresponse:
Unexpecteddata value
Result:=Fail
Result:=Pass
Set negativeresponse:
Data missing
Yes
No
Yes
No
Figure 33: Procedure Check_Parameters
Page 73GSM 03.18 Version 2.1.0: February 1997
Procedure in the HLRto make subscriptionchecks for a mobile-terminated call
Procedure Subscription_Check_HLR SC_HLR1(1)
MSknown?
Set negativeresponse:Unknownsubscriber
Result:=Fail
Numberchanged?
Set negativeresponse:Number changed
Derive_Requested_Basic_Service_HLR
Requestedservice
provisioned?
Set negativeresponse:service notprovisioned
Bearer serviceorTeleservice
Check_IC_Barring
Callbarred?
Set negativeresponse:Call barred
IC_CUG_Check
Callallowed?
Set negativeresponse:
CUG reject
Result:=Pass
No
Yes
Yes
No
No
Yes
Yes
No
No
Yes
Figure 34: Procedure Subscription_Check_HLR
Page 74GSM 03.18 Version 2.1.0: February 1997
Procedure in the HLRto handle call forwardingbefore interrogation of the VLR
Procedure First_Forwarding_HLR FF_HLR1(1)
Handle_CFU
Result=Fail?
Result=Forward?
Result:=Forward
MS notreachable?
Result:=Continue
Handle_CFNRc
Result=Fail?
Result=Forward?
Result:=Forward
Set negativeresponse:
Absentsubscriber
Result:=Fail
Set negativeresponse:
Forwardingviolation
Set negativeresponse:
Forwardingviolation
No
Yes
No
No
Yes
No
Yes
No
Yes
Yes
Figure 35: Procedure First_Forwarding_HLR
Page 75GSM 03.18 Version 2.1.0: February 1997
Procedure in the HLRto handle a negative responsefor a roaming number request
Procedure PRN_Error_HLR PRN_E_H1(1)
Handle_CFNRc
Result=Fail?
Set negativeresponse:
Forwardingviolation
Result:=Fail
Result=Forward?
Set negativeresponse:
Absentsubscriber
Result:=Forward
Negativeresponse=Absentsubscriber?
Handle_CFNRc
Result=Fail?
Result=Forward?
Set negativeresponse:System failure
Result:=Fail
Set negativeresponse:
Forwardingviolation
Set negativeresponse:System failure
Negativeresponse=No roamingnumber?
Set negativeresponse:Facility notsupported
Negativeresponse=Facilitynot supported?
No
Yes
Yes
No
No
Yes
No
Yes
No
Yes
No
Yes
No
Yes
Figure 36: Procedure PRN_Error_HLR
Page 76GSM 03.18 Version 2.1.0: February 1997
Procedure to carry outCUG authorisation checkfor a forwarded call
Procedure Forward_CUG_Check FWD_CUG1(1)
PerformForwarding CUG
authorisation
CUGauthorisation
result
Result:=Call barred
Result:=Call allowed
Update CUGinfo As defined in GSM 03.85
As defined in GSM 03.85
Result:=Call allowed
CUG info provided in routeing informationrequest
CUG provisioned forforwarding subscriber against requested basic service
Yes
Fail
Pass
No
No
Yes
Figure 37: Procedure Forward _CUG_Check
Page 77GSM 03.18 Version 2.1.0: February 1997
Procedure in the HLR to derive the requested basic service for an incoming (MT) call according to the rules of GSM 09.07
Procedure Derive_Requested_Basic_Service_HLR DRBS_H1(1)
ExhaustiveISDN compatibility information available?
Multi-numbering?
GSM BC:=NULL
Basic service:=default
Apply GSM BCfor this
MSISDN
Derive basicservice from
GSM BC
Derive GSM BC fromISDN compatibility
information
No
No
Yes
Yes
Figure 38: Procedure Derive_Requested_Basic_Service_HLR
Page 78GSM 03.18 Version 2.1.0: February 1997
Procedure to check callrequest against SS barring and ODB categories
Procedure Check_IC_Barring CIB1(2)
1
Result:=Call barred
(ODB)
MS registeredin HPLMNzone?
Operator determinedBIC-RoamHZimposed?
1
MS registeredin HPLMNcountry?
Operator determinedBIC-Roam imposed?
Operator determinedBAIC imposed?
No
No
No
Yes
Yes
No
Yes
No
Yes
Yes
Figure 39a: Procedure Check_IC_Barring (sheet 1)
Page 79GSM 03.18 Version 2.1.0: February 1997
Procedure to check callrequest against SS barring and ODB categories
Procedure Check_IC_Barring CIB2(2)
1
Initiatehandling of BAIC
Wait_For_BAIC_
Response
Continuecallhandling
Callbarred?
Initiatehandling of BIC-Roam
Wait_For_BIC-Roam_Response
Continuecallhandling
Callbarred?
Result:=Call barred(SS barring)
Result:=Call allowed
From process MAF023
To process MAF023
From process MAF022
To process MAF022
No
Yes
No
Yes
Figure 39b: Procedure Check_IC_Barring (sheet 2)
Page 80GSM 03.18 Version 2.1.0: February 1997
Procedure to carry outCUG authorisation checkfor an incoming (MT) call
Procedure IC_CUG_Check IC_CUG1(1)
Signals to/from the rightare to/from the processCUG_MAF015
incomingcall
Wait_For_CUG_Response
rejectcall(cause)
Result:=Call barred
(cause)
complete call(conditionalCUG info)
Result:=Call allowed
responseto callrequest
To processCUG_MAF015
Figure 40: Procedure IC_CUG_Check
Page 81GSM 03.18 Version 2.1.0: February 1997
Procedure in the HLRto handle Call ForwardingUnconditional
Procedure Handle_CFU H_CFU1(1)
Signals to/from the rightare to/from the processMAF007 initiate
handlingof CFU
Wait_For_CFU_Result
continuecallhandling
Error?
Normalcall?
Result:=Forward
Result:=Continue
Result:=Fail
No
No
Yes
Yes
Figure 41: Procedure Handle_CFU
Page 82GSM 03.18 Version 2.1.0: February 1997
Procedure in the HLRor VLR to handle CallForwarding on Mobile Subscriber Not Reachable
Procedure Handle_CFNRc H_CFNRc1(1)
Signals to/from the rightare to/from the processMAF010 initiate
handlingof CFNRc
Wait_For_CFNRc_Result
continuecallhandling
Error?
Mobile subscribernot reachable?
Result:=Forward
Result:=Continue
Result:=Fail
No
No
Yes
Yes
Figure 42: Procedure Handle_CFNRc
Page 83GSM 03.18 Version 2.1.0: February 1997
7.2.3 Functional requirements of VLR
7.2.3.1 Process PRN_VLR
Sheet 1: the procedure Check_Parameters is specified in subclause 7.2.2.2.
Sheet 2: the number of unused authentication sets which triggers the VLR to request furtherauthentication sets from the HLR is an operator option.
Sheet 2: the process Fetch_Authentication_Sets_VLR is specified in subclause 7.1.2.15.
7.2.3.2 Process Restore_Subscriber_Data_VLR
7.2.3.3 Process PSI_VLR
Sheet 1: the procedure Check_Parameters is specified in subclause 7.2.2.2.
Sheet 2: the task 'Set Location Info' encompasses:
- Insertion of the cell ID if it was received from the MSC, otherwise retrieval of the stored locationarea ID;
- Derivation of the location number and geographical infornmation from the cell ID or location area IDif the VLR is capable of doing so;
- Insertion of the age of the location information received from the MSC;- Insertion of the VLR number.
Sheet 2: the task ‘Set subscriber state’ consists of inserting the subscriber state if it was received from theMSC, otherwise inserting the state ‘Network determined not reachable’.
Page 84GSM 03.18 Version 2.1.0: February 1997
Process in the VLR to handlea request for a roaming number
Process PRN_VLR PRN_VLR1(3)
Signals to/from the left are to/from the HLR.
Idle
ProvideRoamingNumber
Check_Parameters
Result=Pass?
ORindicatorpresent?
ORsupported?
Convert GSM BCto basic service
If GSM BC was includedin the Provide Roaming Number
Servicesupportedby VLR?
IMSIknown in VLR?
2 IMSIdetached?
Roamingin LA
allowed?
Set negativeresponse:
Absentsubscriber
13
Set negativeresponse:
Facilitynot supported
Set negativeresponse:
OR notallowed
Yes
Yes
Yes
Yes
No
Yes
No
No
Yes
Yes
No
No
No
No
Figure 43a: Process PRN_VLR (sheet 1)
Page 85GSM 03.18 Version 2.1.0: February 1997
Process in the VLR to handlea request for a roaming number
Process PRN_VLR PRN_VLR2(3)
Signals to the left are to the HLR.
2
MSRNavailable
AllocateMSRN
CreateIMSI
record
Dataconfirmed by HLR:=
False
Confirmedby radio
contact:=False
Location infoconfirmedin HLR:=
False
Only if >1 MSCper VLR
IMSIdetached:=
False
Allocate LMSIIf usedby VLR
Storecompatibility
info
GSM BC, ISDN BC,ISDN LLC & ISDN HLC(as available)
ProvideRoamingNumber ack
Fetch_Authentication_
Sets_VLR
Restore_Subscriber_Data_VLR
Idle
Set negativeresponse:
No roamingnumber
Provide RoamingNumbernegative response
Idle
1
4
Moreauthentication sets needed?
Yes
No
Yes
No
Figure 43b: Process PRN_VLR (sheet 2)
Page 86GSM 03.18 Version 2.1.0: February 1997
Process in the VLR to handlea request for a roaming number
Process PRN_VLR PRN_VLR3(3)
Signals to the left are to the HLR.
3
MSRNavailable
MSCper VLR
Received MSC number=Stored MSC number
Confirmed byradio contact
Use receivedMSC number
for MSRN
AllocateMSRN
Storecompatibility
info
GSM BC, ISDN BC,ISDN LLC & ISDN HLC(as available)
ProvideRoamingNumber ack
Dataconfirmed
by HLR
Idle 4
Use storedMSC number
for MSRN
Set negativeresponse:
No roamingnumber
Provide RoamingNumbernegative response
Idle
Yes
>1
No
False
True
False
True
Yes
1
No
Figure 43c: Process PRN_VLR (sheet 3)
Page 87GSM 03.18 Version 2.1.0: February 1997
Process in the VLRto restore subscriber data
Process Restore_Subscriber_Data_VLR RSD_VLR1(1)
Signals to/from the leftare to/from the HLR
RestoreData
Wait_For_Data
RestoreData ack
UpdateSubscriber
Data
UpdateHLR
number
Update MSNot Reachable
indicator
If receivedfrom HLR
Data confirmed by HLR:=True
RestoreData negativeresponse
Figure 44: Process Restore_Subscriber_Data_VLR
Page 88GSM 03.18 Version 2.1.0: February 1997
Process in the VLR to handlea request from the HLR forsubscriber information
Process PSI_VLR PSI_VLR1(2)
Signals to/from the leftare to/from the HLR; signals to/from the rightare to/from the MSC
Idle
ProvideSubscriberInfo
Check_Parameters
Result=Pass?
IMSIknown
in VLR?
Subscriberstate
requested?
IMSIdetached?
Roamingin LA
allowed?
Set subscriberstate
requested
Location info
requested?
Set subscriberstate
requested
ObtainSubscriberInfo
Wait_For_MSC_Response
Subscriber atate:=Network determined
not reachable
Location info
requested?
ProvideSubscriberInfo ack
Idle
Subscriberstate
requested?
Subscriber state:=Assumed idle
ProvideSubscriberInfo negativeresponse
Idle
Yes
Yes
Yes
No
Yes
Yes
No
Yes
No
Yes
No
No
Yes
No
No
Figure 45a: Process PSI_VLR (sheet 1)
Page 89GSM 03.18 Version 2.1.0: February 1997
Process in the VLR to handlea request from the HLR forsubscriber information
Process PSI_VLR PSI_VLR2(2)
Signals to/from the leftare to/from the HLR; signals to/from the rightare to/from the MSC
Wait_For_MSC_Response
ObtainSubscriberInfo ack
Locationinfo
received?
Setlocation
info
Subscriberstate
received?
Setsubscriber
state
ProvideSubscriberInfo ack
Idle
Yes
Yes
No
No
Figure 45b: Process PSI_VLR (sheet 2)
Page 90GSM 03.18 Version 2.1.0: February 1997
7.2.4 Functional requirements of MSC
7.2.4.1 Process OSI_MSC
If the MS is engaged on a circuit-switched call, the state is busy, otherwise assumed idle.
Page 91GSM 03.18 Version 2.1.0: February 1997
Process in the MSC to handlea request from the VLR forinformation on the subscriber's location and state
Process OSI_MSC OSI_MSC1(1)
Signals to/from the leftare to/from the VLR
Idle
ObtainSubscriberInfo
Locationinfo
requested?
Set age of location info
MS inradio
contact?
Set cellglobalidentity
Subscriberstate
requested?
Setsubscriber
state
ObtainSubscriberInfo ack
Idle
Yes
Yes
Yes
No
No
No
Figure 46: Process OSI_MSC
Page 92GSM 03.18 Version 2.1.0: February 1997
7.3 MT call
7.3.1 Functional requirements of serving MSC
7.3.1.1 Process ICH_MSC
Sheet 1: the rules for converting the ISDN BC/LLC/HLC to a GSM bearer service or teleservice arespecified in [18].
Sheet 1: the procedure Process_Access_Request_MSC is specified in subclause 7.1.1.2.
Sheet 2: the suggested mapping from values of the Send Info For Incoming Call negative responseinformation element to values of the ISUP release cause (see [22]) is shown in table 2. The mapping usedis a matter for the network operator, depending on the telephony signalling system used.
Table 2: Suggested mapping of Send Info For Incoming Call (SIFIC) negative responses to ISUPrelease causes
SIFIC negative response ISUP release cause number ISUP release cause nameAbsent subscriber 20 Subscriber absentBusy subscriber 17 User busyCUG reject (Called party SSinteraction violation)
21 Call rejected
Forwarding violation 21 Call rejectedImpossible call completion 111 Protocol error, unspecifiedNo subscriber reply 19 No answer from user (user alerted)System failure 111 Protocol error, unspecifiedUnallocated roaming number 111 Protocol error, unspecified
Sheet 3: the procedure Handle_COLP_Forwarding_Interaction is specified in subclause 7.2.1.2.
Sheet 5: after the VMSC has sent an IAM to the forwarded-to exchange, it acts as a transparent relay formessages received from the GMSC and the forwarded-to exchange. Any message other than AddressComplete, Connect, Answer or Release causes no change of state in the process ICH_MSC.
7.3.1.2 Procedure Page_MS_MSC
Sheet 1: For an SMS or SS page, the test 'Call still exists' takes the 'Yes' exit if the SMS or SS transactionwhich led to the page still exists.
Sheet 1: the test ‘SMS or SS page’ is not required for the handling of circuit-switched calls, because theVLR will always use a page type of ‘circuit-switched call’, but the more generalised procedurePage_MS_MSC is equally applicable to paging for SMS delivery or network-initiated SS procedures.
Sheet 1: the test ‘MS busy’ takes the ‘Yes’ exit if the MS is engaged on a circuit-switched call.
Sheet 1: the test ‘Call in setup’ takes the ‘Yes’ exit if the call on which the MS is engaged has not reachedthe established phase (called party answer).
Sheet 1: the test Call waiting’ takes the ‘Yes’ exit if a waiting call has been offered to the subscriber butthe outcome of offering the call has not been determined.
Sheet 1: the negative response Busy Subscriber (More calls possible) includes the basic service whichapplies for the established call.
Sheet 2: the signal input ‘MS connection established’ indicates that the MS has responded to paging, orsent a CM sevice request for anything other than a circuit-switched call, or completed the locationregistration procedure.
Page 93GSM 03.18 Version 2.1.0: February 1997
7.3.1.3 Procedure Search_For_MS_MSC
Sheet 1: For an SMS or SS page, the test 'Call still exists' takes the 'Yes' exit if the SMS or SS transactionwhich led to the page still exists.
Sheet 1: the test ‘SMS or SS page’ is not required for the handling of circuit-switched calls, because theVLR will always use a page type of ‘circuit-switched call’, but the more generalised procedureSearch_For_MS_MSC is equally applicable to paging for SMS delivery or network-initiated SSprocedures.
Sheet 1: the test ‘MS busy’ takes the ‘Yes’ exit if the MS is engaged on a circuit-switched call.
Sheet 1: the test ‘Call in setup’ takes the ‘Yes’ exit if the call on which the MS is engaged has not reachedthe established phase (called party answer).
Sheet 1: the test Call waiting’ takes the ‘Yes’ exit if a waiting call has been offered to the subscriber butthe outcome of offering the call has not been determined.
Sheet 1: the negative response Busy Subscriber (More calls possible) includes the basic service whichapplies for the established call.
Sheet 2: the signal input ‘MS connection established’ indicates that the MS has responded to paging, orsent a CM sevice request for anything other than a circuit-switched call, or completed the locationregistration procedure.
7.3.1.4 Procedure Complete_Call_In_MSC
Sheet 1: the MSC and the MS may negotiate the bearer capability to be used for the call by the exchangeof information in the Setup and Call Confirmed messages.
7.3.1.5 Procedure Process_Call_Waiting_MSC
Sheet 1: the MSC and the MS may negotiate the bearer capability to be used for the call by the exchangeof information in the Setup and Call Confirmed messages.
Sheet 1: the Call Confirmed message indicates 'busy' for the successful case.
Sheets 1 & 2: the Release transaction (reject) message covers all unsuccessful cases not otherwiseindicated.
7.3.1.6 Procedure Set_CLIP_Info_MSC
The originating exchange may release the call or the MS may terminate the transaction with the networkby sending a Release transaction message while a response is awaited from the process CLIP_MAF002.The message is saved for processing after return from the procedure.
7.3.1.7 Procedure Derive_GSM_BC_MSC
7.3.1.8 Procedure Handle_AoC_MT_MSC
7.3.1.9 Procedure Set_COL_Presentation_Indicator_MSC
The originating exchange may release the call or the MS may terminate the transaction with the networkby sending a Release transaction message while a response is awaited from the process COLP_MAF041.The message is saved for processing after return from the procedure.
Page 94GSM 03.18 Version 2.1.0: February 1997
Process in the MSCto handle an incoming (MT) call
Process ICH_MSC ICH_MSC1(5)
Signals to/from the leftare to/from the BSS; signals to/from the rightare to/from the VLRunless marked otherwise
Idle
InitialAddress From GMSC
Convert ISDN BC/LLC/HLC(if present) to GSM bearer service/teleservice& GSM BC
Send InfoFor IncomingCall
Wait_For_Page_Request
Send InfoFor IncomingCall negativeresponse
Setcause
Release To GMSC
Release callresources
Idle
Page MS
Page_MS_MSC
Result=Pass?
Process_Access_
Request_MSC
Result=Pass?
Wait_For_MT_Call_
Result
Release To GMSC
Release callresources
Idle
Result=Fail?
Release callresources
Idle
Wait_For_MT_Call_
Result
SearchFor MS
Search_For_MS_MSC
Result=Pass?
Result=Fail
Wait_For_MT_Call_
Result
Release callresources
Idle
Yes
Yes
No
No
No
Yes
Yes
No
Yes
No
Figure 47a: Process ICH_MSC (sheet 1)
Page 95GSM 03.18 Version 2.1.0: February 1997
Process in the MSCto handle an incoming (MT) call
Process ICH_MSC ICH_MSC2(5)
Signals to/from the leftare to/from the BSS; signals to/from the rightare to/from the VLRunless marked otherwise
Wait_For_MT_Call_
Result
Send InfoFor IncomingCall negativeresponse
Set cause
ReleaseTo GMSC
Releasetransaction
Release call
resources
Idle
CompleteCall
Complete_Call_In_MSC
Result=Pass?
Result=Fail
Wait_For_MT_Call_
Result
Send InfoFor IncomingCall ack
Call is to beforwarded
Set redirectioninformation
Addresscomplete
InitialAddressMessage
Towards exchange defined byforwarded-to number
Wait_For_ACM
Release call
resources
Idle
Wait_For_Clear
ProcessCallWaiting
Process_Call_
Waiting_MSC
Result=Pass?
Result=Fail
Release call
resources
Idle
Wait_For_Clear
No
Yes
No
Yes
No
Yes
No
Yes
Figure 47b: Process ICH_MSC (sheet 2)
Page 96GSM 03.18 Version 2.1.0: February 1997
Process in the MSCto handle an incoming (MT) call
Process ICH_MSC ICH_MSC3(5)
Signals to/from the leftare to/from the GMSC;signals to/from the rightare to/from the destination exchange
Wait_For_ACM
Release Release AddressComplete
Connect
Release ReleaseAddressComplete
Release callresources
Start Answerguard timer
Idle Wait_For_Answer
Release Release Answer
Release ReleaseHandle_COLP_
Forwarding_Interaction_MSC
Handle_COLP_Forwarding_
Interaction_MSC
Release callresources
Set COLPpresentation
indicator
Set COLPpresentation
indicator
Idle Answer Connect
Wait_For_Forwarded_Clear
Figure 47c: Process ICH_MSC (sheet 3)
Page 97GSM 03.18 Version 2.1.0: February 1997
Process in the MSCto handle an incoming (MT) call
Process ICH_MSC ICH_MSC4(5)
Signals to/from the leftare to/from the BSS;signals to/from the rightare to/from the VLRunless otherwise indicated
Wait_For_MT_Call_Result,Wait_For_Clear
Releasetransaction
Release To GMSC
Abort
Releasecall
resources
Idle
Release From GMSC
Releasetransaction
Wait_For_Forwarded_Clear
Release From GMSC
ReleaseTowards destinationexchange
Releasecall
resources
Idle
Release From destinationexchange
Release To GMSC
Figure 47d: Process ICH_MSC (sheet 4)
Page 98GSM 03.18 Version 2.1.0: February 1997
Process in the MSCto handle an incoming (MT) call
Process ICH_MSC ICH_MSC5(5)
Signals to/from the leftare to/from the GMSC;signals to/from the rightare to/from the destination exchange
Wait_For_ACM,Wait_For_Answer,Wait_For_Forwarded_Clear
*
-
-
*
-
Figure 47e: Process ICH_MSC (sheet 5)
Page 99GSM 03.18 Version 2.1.0: February 1997
Procedure in the MSCto page an MS in aspecified location area
Procedure Page_MS_MSC PAGE_M1(2)
Signals to/from the leftare to/from the BSS; signals to/from the rightare to/from the VLRunless marked otherwise
Locationarea IDknown?
Set negativeresponse:
Unknown LAI
Page MSnegativeresponse
Result:=Fail
Callstill
exists?
Set negativeresponse:SystemFailure
MSconnection
exists?
SMS or SSpage?
MS busy?
Call insetup?
Callwaiting?
Set negativeresponse:
Busy Subscriber
More callspossible
Set negativeresponse:
Busy Subscriber(NDUB)
Set accessconnection
status
Result:=Pass
Clear received:=False
PageIn specified location area
Start Pageresponse
timer
Wait_For_Page_
Response
No
Yes
No
Yes
Yes
No
Yes
No
No
Yes
Yes
No
Yes
No
Figure 48a: Procedure Page_MS_MSC (sheet 1)
Page 100GSM 03.18 Version 2.1.0: February 1997
Procedure in the MSCto page an MS in aspecified location area
Procedure Page_MS_MSC PAGE_M2(2)
Signals to/from the leftare to/from the BSS; signals to/from the rightare to/from the VLRunless marked otherwise
Wait_For_Page_
Response
MSconnectionestablished
Clearreceived
Set accessconnection
status
Result:=Pass
Releasetransaction
Result:=Aborted
Release From GMSC
Abort
Clear received:=True
Wait_For_Page_
Response
Pageresponsetimer expired
Clearreceived
Set negativeresponse:
AbsentSubscriber
Page MSnegativeresponse
Result:=Fail
Result:=Aborted
CM ServiceRequest
For circuit-switched call
CM ServiceRequest
To process OCH_MSC
Clearreceived
Set negativeresponse:
Busy Subscriber(NDUB)
Page MSnegativeresponse
Result:=Fail
Result:=Aborted
False
True
False
True
False
True
Figure 48b: Procedure Page_MS_MSC (sheet 2)
Page 101GSM 03.18 Version 2.1.0: February 1997
Procedure in the MSCto search for an MS (page in all location areas)
Procedure Search_For_MS_MSC SRCH_M1(2)
Signals to/from the leftare to/from the BSS; signals to/from the rightare to/from the VLRunless marked otherwise
Callstill
exists?
MSconnection
exists?
SMS or SSpage?
MS busy?
Call insetup?
Callwaiting?
Set negativeresponse:
Busy Subscriber
More callspossible
SearchFor MSnegativeresponse
Result:=Fail
Set negativeresponse:
Busy Subscriber(NDUB)
Set accessconnection
status
Result:=Pass
Clear received:=False
PageIn alllocation areas
Start Pageresponse
timer
Wait_For_Search_
Response
Set negativeresponse:SystemFailure
Yes
Yes
No
Yes
No
No
Yes
Yes
No
Yes
No
No
Figure 49a: Procedure Search_For_MS_MSC (sheet 1)
Page 102GSM 03.18 Version 2.1.0: February 1997
Procedure in the MSCto search for an MS (page in all location areas)
Procedure Search_For_MS_MSC SRCH_M2(2)
Signals to/from the leftare to/from the BSS; signals to/from the rightare to/from the VLRunless marked otherwise
Wait_For_Search_
Response
MSconnectionestablished
Clearreceived
Search For MS ack
Set accessconnection
status
Result:=Pass
Releasetransaction
Result:=Aborted
Release From GMSC
Abort
Clear received:=True
Wait_For_Search_
Response
Pageresponsetimer expired
Clearreceived
Set negativeresponse:
AbsentSubscriber
Search For MS negativeresponse
Result:=Fail
Result:=Aborted
CM ServiceRequest
For circuit-switched call
CM ServiceRequest
To process OCH_MSC
Clearreceived
Set negativeresponse:
Busy Subscriber(NDUB)
Search For MS negativeresponse
Result:=Fail
Result:=Aborted
False
True
False
True
False
True
Figure 49b: Procedure Search_For_MS_MSC (sheet 2)
Page 103GSM 03.18 Version 2.1.0: February 1997
Procedure in the MSCto complete an MT call on request from the VLR
Procedure Complete_Call_In_MSC CCI_MSC1(4)
Signals to/from the leftare to/from the BSS; signals to/from the rightare to/from the VLRunless marked otherwise
Set_CLIP_Info_MSC
Setup
Wait_For_Setup_
Response
CallConfirmed
Allocatechannel
Wait_For_Allocation_Complete
Setup failure
Set negativeresponse:
AbsentSubscriber
CompleteCallnegativeresponse
Result:=Fail
Derive_GSM_BC_
MSC
Figure 50a: Procedure Complete_Call_In_MSC (sheet 1)
Page 104GSM 03.18 Version 2.1.0: February 1997
Procedure in the MSCto complete an MT call on request from the VLR
Procedure Complete_Call_In_MSC CCI_MSC2(4)
Signals to/from the leftare to/from the BSS; signals to/from the rightare to/from the VLRunless marked otherwise
Wait_For_Allocation_Complete
AllocationComplete
Wait_For_Alerting
Alerting
NRCTprovided?
Start No ReplyCall Timer
AddressComplete To GMSC
Wait_for_Answer
Connect
Handle_AoC_MT_MSC
Result=Pass?
Connectack
Set_COL_Presentation_Indicator_MSC
ConnectTo GMSC
CompleteCallack
Result:=Pass
Release To GMSC
Abort
Result:=Aborted
Alertingfailure
Abort
Release To GMSC
Result:=Aborted
Allocationfailure
Set negativeresponse:
Radiocongestion
CompleteCallnegativeresponse
Result:=Fail
Yes
No
Yes
No
Figure 50b: Procedure Complete_Call_In_MSC (sheet 2)
Page 105GSM 03.18 Version 2.1.0: February 1997
Procedure in the MSCto complete an MT call on request from the VLR
Procedure Complete_Call_In_MSC CCI_MSC3(4)
Signals to/from the leftare to/from the BSS; signals to/from the rightare to/from the VLRunless marked otherwise
Wait_for_Answer
No ReplyCall Timerexpired
Set negativeresponse:
No subscriberreply
CompleteCallnegativeresponse
Result:=Fail
Connect
Handle_AoC_MT_MSC
Result=Pass?
Connectack
Set_COL_Presentation_Indicator_MSC
Answer To GMSC
CompleteCallack
Result:=Pass
Release To GMSC
Abort
Result:=Aborted
Yes
No
Figure 50c: Procedure Complete_Call_In_MSC (sheet 3)
Page 106GSM 03.18 Version 2.1.0: February 1997
Procedure in the MSCto complete an MT call on request from the VLR
Procedure Complete_Call_In_MSC CCI_MSC4(4)
Signals to/from the leftare to/from the BSS; signals to/from the rightare to/from the VLRunless marked otherwise
Wait_For_Setup_Response,Wait_For_Assignment_Complete,Wait_For_Alerting,Wait_For_Answer
Releasetransaction
Userbusy?
Set negativeresponse:
Busy subscriber(UDUB)
CompleteCallnegativeresponse
Result:=Fail
Release To GMSC
Abort
Releasecall
resources
Result:=Aborted
Release From GMSC
Releasetransaction
Yes
No
Figure 50d: Procedure Complete_Call_In_MSC (sheet 4)
Page 107GSM 03.18 Version 2.1.0: February 1997
Procedure in the MSCto handle a Process Call Waitingrequest from the VLR
Procedure Process_Call_Waiting_MSC PCW_MSC1(3)
Signals to/from the leftare to/from the BSS; signals to/from the rightare to/from the VLRunless marked otherwise
Call beingset up
Set negativeresponse:
Busysubscriber
ProcessCall Waitingnegativeresponse
Result:=Fail
Set_CLIP_Info_MSC
Setup
Wait_For_Setup_
Response
CallConfirmed
Wait_For_Alerting
Alerting
NRCTprovided?
StartNo ReplyCall Timer
AddressComplete
To GMSC ofwaiting call
Wait_For_Acceptance
StartAcceptance
timer
Alertingfailure
Abort
ReleaseTo GMSC ofwaiting call
Result:=Aborted
Releasetransaction(UDUB)
Set negativeresponse:
Busysubscriber
ProcessCall Waitingnegativeresponse
Result:=Fail
Releasetransaction(reject)
Release To GMSC ofwaiting call
Abort
Result:=Aborted
Setup failure
Clearpendingcall
Derive_GSM_BC_
MSC
Yes
No
Yes
No
Figure 51a: Procedure Process_Call_Waiting_MSC (sheet 1)
Page 108GSM 03.18 Version 2.1.0: February 1997
Procedure in the MSCto handle a Process Call Waitingrequest from the VLR
Procedure Process_Call_Waiting_MSC PCW_MSC2(3)
Signals to/from the leftare to/from the BSS; signals to/from the rightare to/from the VLRunless marked otherwise
Wait_for_Acceptance
Connect
Assignmentrequired?
Allocate channel
Wait_For_Allocation_Complete
AllocationComplete
Handle_AoC_MT_MSC
Result=Pass?
Connectack
Set_COL_Presentation_Indicator_MSC
Answer To GMSC ofwaiting call
Process CallWaiting ack
Result:=Pass
Release To GMSC ofwaiting call
Abort
Result:=Aborted
Allocationfailure
Yes
Yes
No
No
Figure 51b: Procedure Process_Call_Waiting_MSC(sheet 2)
Page 109GSM 03.18 Version 2.1.0: February 1997
Procedure in the MSCto handle a Process Call Waitingrequest from the VLR
Procedure Process_Call_Waiting_MSC PCW_MSC3(3)
Signals to/from the leftare to/from the BSS; signals to/from the rightare to/from the VLRunless marked otherwise
Wait_for_Acceptance
Releasetransaction(busy)
Set negativeresponse:
Busysubscriber
ProcessCall Waitingnegativeresponse
Result:=Fail
Releasetransaction(reject)
Release To GMSC ofwaiting call
Abort
Result:=Aborted
Acceptance timer expired
Clearpendingcall
No ReplyCall Timerexpired
Set negativeresponse:
No subscriberreply
ProcessCall Waitingnegativeresponse
Result:=Fail
Wait_For_Setup_Response,Wait_For_Assignment_Complete,Wait_For_Alerting,Wait_For_Acceptance
Release From GMSC ofwaiting call
Clearpendingcall
Abort
Result:=Aborted
Figure 51c: Procedure Process_Call_Waiting_MSC(sheet 3)
Page 110GSM 03.18 Version 2.1.0: February 1997
Procedure in the MSCto determine the CLIPinformation to be sent to the MS
Procedure Set_CLIP_Info_MSC CAINF_M1(1)
Signals to/from the rightare to/from the processCLIP_MAF002 Initiate
handlingof CLIP
Wait_For_CLIP_Info
Releasetransaction
From BSSContinuecallhandling
Release From GMSC
Figure 52: Procedure Set_CLIP_Info_MSC
Page 111GSM 03.18 Version 2.1.0: February 1997
Procedure in the MSC toderive the requested GSM BCfor an incoming (MT) call according to the rules ofGSM 09.07
Procedure Derive_GSM_BC_MSC DRBC_M1(1)
GSM BC derived from ISDN compatibility information?
Use GSM BCderived from
ISDN compatibilityinformation
GSM BC receivedin PRN?
Omit GSM BCfrom Setup
Use GSM BCreceived in PRN
Yes
No
No
Yes
Figure 53: Derive_GSM_BC_MSC
Page 112GSM 03.18 Version 2.1.0: February 1997
Procedure in the MSCto handle AoC signalling towards the MS for an MT call
Procedure Handle_AoC_MT_MSC AOCMT_M1(1)
Signals to/from the leftare to/from the BSS;signals from the rightare from the AoC timer function.
AoC(I)provisioned?
Setcharging
parameters
SendChargingParameters
Result:=Pass
AoC(C)provisioned?
Setcharging
parameters
SendChargingParameters
Start AoCacknowledgment
timer
Wait_For_Charging_
Parameters_Ack
Charging Parametersack
Releaseconnection
Result:=Fail
AoCacknowledgmenttimer expired
Releasetransaction
Yes
No
No
Yes
Figure 54: Procedure Handle_AoC_MT_MSC
Page 113GSM 03.18 Version 2.1.0: February 1997
Procedure in the MSCto determine the COL presentation indicator value
Procedure Set_COL_Presentation_Indicator_MSC COIND_M1(1)
Signals to/from the rightare to/from the processCOLR_MAF041 Initiate
handlingof COLR
Wait_For_COLR_Info
Releasetransaction
From BSSContinuecallhandling
Release From GMSC
Figure 55: Procedure Set_COL_Presentation_Indicator MSC
Page 114GSM 03.18 Version 2.1.0: February 1997
7.3.2 Functional requirements of VLR
7.3.2.1 Process ICH_VLR
Sheet 1: if the MSRN received in the Send Info For Incoming Call is not allocated or there is no IMSIrecord for the IMSI identified by the MSRN, this is treated as an unknown MSRN.
Sheet 2: the procedure Process_Access_Request_VLR is specified in subclause 7.1.2.2.
Sheet 2: the test 'NDUB?' takes the 'Yes' exit if the Page MS negative response or the Search for MSnegative response had the value Busy Subscriber (NDUB).
Sheet 2: the VLR uses the basic service returned in the Page MS negative response or the Search for MSnegative response Busy Subscriber (More calls possible) to determine whether call waiting is available.
Sheet 2: the procedure Get_AoC_Subscription_Info_VLR is specified in subclause 7.1.2.7.
Sheet 5: the procedure Handle_CFNRc is specified in subclause 7.2.2.11.
Sheet 6: the procedure Forward_CUG_Check is specified in subclause 7.2.2.6.
7.3.2.2 Procedure Derive_Requested_Basic_Service_VLR
If the VLR did not receive a basic service for the call in the Send Info For Incoming Call, and did notreceive a GSM bearer capability in the Provide Roaming Number, it applies a default basic serviceaccording to the requirements of the operator.
7.3.2.3 Procedure Search_For_MS_VLR
7.3.2.4 Procedure Get_CW_Subscription_Info_VLR
The MSC may abort the transaction with the VLR while a response is awaited from the process MAF013.The message is saved for processing after return from the procedure.
7.3.2.5 Procedure Get_LI_Subscription_Info_MT_VLR
The MSC may abort the transaction with the VLR while a response is awaited from the processCLIP_MAF001 or the process COLR_MAF040. The message is saved for processing after return from theprocedure.
7.3.2.6 Procedure Handle_CFB
The test ‘Normal call busy’ refers to the value of the indicator returned by the process MAF008.
7.3.2.7 Procedure Handle_CFNRy
The test ‘Normal call’ refers to the value of the indicator returned by the process MAF009.
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Process in VLRB tohandle a request for informationfor an incoming (MT) call
Process ICH_VLR ICH_VLR1(6)
Signals to/from the leftare to/from the MSC.
Idle
Send InfoFor IncomingCall
MSRNknown?
Dataconfirmed
by HLR
Set negativeresponse:SystemFailure
Send InfoFor IncomingCall negativeresponse
Idle
Derive_Requested_Basic_Service_VLR
IMSIdetached?
Roamingin LA
allowed?
Locationarea IDknown?
Search_For_MS_VLR
Result=Pass?
Result=Fail?
Idle 2Wait_For_Access_Request
Page MS Page type=circuit-switched call
1
Set negativeresponse:
UnallocatedRoaming Number
Yes
False
True
No
Yes
No
No
No
Yes
Yes
Yes
No
Yes
No
Figure 56a: Process ICH_VLR (sheet 1)
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Process in VLRB tohandle a request for informationfor an incoming (MT) call
Process ICH_VLR ICH_VLR2(6)
Signals to/from the leftare to/from the MSC.
Wait_For_Access_Request
Page MSnegativeresponse
Absentsubscriber?
1
Busysubscriber?
3
NDUB?
Get_CW_Subscription_
Info_VLR
CWavailable?
Get_LI_Subscription_Info_MT_VLR
Get_AoC_Subscription_
Info_VLR
4 5
ProcessAccessRequest
Process_Access_
Request_VLR
Result=Pass?
CUGinfo
present?
Translate CUGinterlockto index
As defined in GSM 03.85
Success?
CFNRyA&O?
ProvideNRCTvalue
Get_LI_Subscription_Info_MT_VLR
Get_AoC_Subscription_
Info_VLR
CompleteCall
Wait_For_Complete_Call_
Result
Set negativeresponse:
System failure
Send InfoFor IncomingCall negativeresponse
Idle
Idle
Abort2
3
Yes
No
No
Yes
No
Yes
No
Yes
Yes
Yes
Yes
Yes
No
No
No
No
Figure 56b: Process ICH_VLR (sheet 2)
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Process in VLRB tohandle a request for informationfor an incoming (MT) call
Process ICH_VLR ICH_VLR3(6)
Signals to/from the leftare to/from the MSC.
Wait_for_Complete_Call
Result
CompleteCall ack
Idle
AbortCompleteCall negativeresponse
Busysubscriber?
Absentsubscriber?
Radiocongestion?
Nosubscriber
reply?
Set negativeresponse:
Impossible callcompletion
Send InfoFor IncomingCall negativeresponse
Idle 6 1 5
No
No
No
No
Yes
Yes
Yes
Yes
Figure 56c: Process ICH_VLR (sheet 3)
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Process in VLRB tohandle a request for informationfor an incoming (MT) call
Process ICH_VLR ICH_VLR4(6)
Signals to/from the leftare to/from the MSC.
4
CFNRyA&O?
Set NRCT
ProcessCallWaiting
Wait_For_PCW_Result
ProcessCallWaiting ack
Idle
Abort
ProcessCall Waiting negativeresponse
Busysubscriber?
Nosubscriber
reply?
Set negativeresponse:
Impossible callcompletion
Send InfoFor IncomingCall negativeresponse
Idle 6 5
Yea
No
No
Yes
Yes
No
Figure 56d: Process ICH_VLR (sheet 4)
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Process in VLRB tohandle a request for informationfor an incoming (MT) call
Process ICH_VLR ICH_VLR5(6)
1
Handle_CFNRc
Result=Fail?
Set negativeresponse:
ForwardingViolation
Send InfoFor IncomingCall negativeresponse
Idle
Result=Forward?
Set negativeresponse:
AbsentSubscriber
7
5
Handle_CFB
Result=Fail?
Set negativeresponse:
ForwardingViolation
Result=Forward?
Set negativeresponse:
Busy Subscriber
7
6
Handle_CFNRy
Result=Fail?
Set negativeresponse:
ForwardingViolation
Result=Forward?
Set negativeresponse:
No SubscriberReply
7
Yes
No
No
YesYes
No
No
Yes
Yes
No
No
Yes
Figure 56e: Process ICH_VLR (sheet 5)
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Process in VLRB tohandle a request for informationfor an incoming (MT) call
Process ICH_VLR ICH_VLR6(6)
Signals to the leftare to the MSC.
7
Forward_CUG_Check
Callallowed?
Set result:Forward
Setforwardinginformation
Send InfoFor IncomingCall ack
Idle
Set negativeresponse:CUG reject
Send InfoFor IncomingCall negativeresponse
Idle
Yes
No
Figure 56f: Process ICH_VLR (sheet 6)
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Procedure in the VLR to derive the requested basic service for an incoming (MT) call
Procedure Derive_Requested_Basic_Service_VLR DRBS_V1(1)
Basic service included inSend Info For Incoming Call?
Basic service:=BS received in
SIFIC
GSM BC received inProvide Roaming Number
Basic service:=BS derived from
GSM BC
Basic service:=default
Yes
No
Yes
No
Figure 57: Procedure Derive_Requested_Basic_Service_VLR
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Procedure in the VLRto search for an MS (i.e. page in all location areas)
Procedure Search_For_MS_VLR SRCH_V1(1)
Signals to/from the leftare to/from the MSC
Search For MS
Page type=Circuit-switched call
Wait_For_Search_Result
Abort
Result:=Aborted
SearchFor MS negativeresponse
Result:=Fail
SearchFor MS ack
UpdateLocationArea ID
Result:=Pass
Figure 58: Procedure Search_For_MS_VLR
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Procedure in the VLR to retrieve subscription information for the Call Waiting service
Procedure Get_CW_Subscription_Info_VLR CWI_VLR1(1)
Signals to/from the rightare to/from the processMAF013 initiate
handlingof CW
Wait_For_CW_Info
Abortprocesscallwaiting
From MSC
Figure 59: Procedure Get_CW_Subscription_Info_VLR
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Procedure in the VLRto retrieve subscription information for the CLIP & COLR line identificationservices for an MT call
Procedure Get_LI_Subscription_Info_MT_VLR GLI_MTV1(1)
Initiatehandling of CLIP
Wait_For_CLIP_Info
AbortContinuecallhandling
Initiatehandling of COLR
Wait_For_COLR_Info
AbortContinuecallhandling
From process COLR_MAF040
To process COLR_MAF040
From process CLIP_MAF001
To process CLIP_MAF001
From MSC
From MSC
Figure 60: Procedure Get_LI_Subscription_Info_MT_VLR
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Procedure in the VLRto handle Call Forwardingon Busy
Procedure Handle_CFB H_CFB1(1)
Signals to/from the rightare to/from the processMAF008 initiate
handlingof CFB
Wait_For_CFB_Result
continuecallhandling
Error?
Normalcall
busy?
Result:=Continue
Result:=Forward
Result:=Fail
No
Yes
No
Yes
Figure 61: Procedure Handle_CFB
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Procedure in the VLRto handle Call Forwardingon No subscriber Reply
Procedure Handle_CFNRy H_CFNRy1(1)
Signals to/from the rightare to/from the processMAF009 initiate
handlingof CFNRy
Wait_For_CFNRy_Result
continuecallhandling
Error?
Normalcall?
Result:=Continue
Result:=Forward
Result:=Fail
No
Yes
No
Yes
Figure 62: Procedure Handle_CFNRy
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8 Contents of messages
This clause specifies the content of each message shown in clauses 5 & 7, except for the followingmessages, which are not specific to call handling:
On the D interface (VLR-HLR):- Abort;- Activate Trace Mode- Insert Subscriber Data- Send Authentication Info;- Send Authentication Info ack;- Send Authentication Info negative response;
In the tables which follow, information elements are shown as mandatory (M), conditional (C) or optional(O). A mandatory information element shall always be present. A conditional information element shall bepresent if certain conditions are fulfilled; if those conditions are not fulfilled it shall be absent. An optionalelement may be present or absent, at the discretion of the application at the sending entity.
8.1 Messages on the B interface (MSC-VLR)
8.1.1 Abort
The following information element is required:
Information element name Required DescriptionAbort reason M Indicates the reason for the procedure being aborted.
8.1.2 Authenticate
The following information elements are required:
Information element name Required DescriptionRAND M Random number challenge to be sent to the MS [3]CKSN M Cipher key sequence number to be sent to the MS [3]
8.1.3 Authenticate ack
The following information element is required:
Information element name Required DescriptionSRES M Signature result returned by the MS [3]
8.1.4 Check IMEI
This message contains no information elements.
8.1.5 Check IMEI ack
The following information element is required:
Information element name Required DescriptionEquipment status M Indicates whether the ME is black-listed, grey-listed or
white-listed
8.1.6 Check IMEI negative response
The negative response information element can take the following values:
- System failure;- Unknown equipment.
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8.1.7 Complete Call
The following information elements are required:
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Information element name Required DescriptionMSISDN C MSISDN of the MS for which the Complete Call is sent.
Shall be present for an ordinary MO call, for an MT call andfor an emergency call when the MS is registered in theVLR; otherwise shall be absent.
IMEI C IMEI of the mobile for which the Complete Call is sent.Shall be present for an emergency call when the mobile isidentified only by its IMEI; otherwise shall be absent.
Category C Category of the MS for which the Complete Call is sent.Shall be present for an ordinary MO call and for anemergency call when the MS is registered in the VLR;otherwise shall be absent.
GSM bearer capability C Shall be present for an MT call if it was received in theProvide Roaming Number; otherwise shall be absent.
ISDN bearer capability C Shall be present for an MT call if it was received in theProvide Roaming Number; otherwise shall be absent.
ISDN low layer compatibility C Shall be present for an MT call if it was received in theProvide Roaming Number; otherwise shall be absent.
ISDN high layer compatibility C Shall be present for an MT call if it was received in theProvide Roaming Number; otherwise shall be absent.
CLIP provision C Indicates that CLIP is provisioned. Shall be present for anMT call if CLIP is provisioned; otherwise shall be absent.
CLIR override provision C Indicates that the CLIR override subscription option ofCLIP is provisioned. Shall be present for an MT call if CLIPis provisioned with the CLIR override subscription optionand the MS is registered in the HPLMN country; otherwiseshall be absent.
CLIR provision C Indicates that CLIR is provisioned. Shall be present for anMO call if CLIR is provisioned; otherwise shall be absent.
CLIR mode C Indicates the mode in which CLIR is provisioned:permanent, temporary (default presentation allowed) ortemporary (default presentation restricted). Shall bepresent for an MO call if CLIR is provisioned; otherwiseshall be absent.
COLP provision C Indicates that COLP is provisioned. Shall be present for anMO call if COLP is provisioned; otherwise shall be absent.
COLR override provision C Indicates that the COLR override subscription option ofCOLP is provisioned. Shall be present for an MO call ifCOLP is provisioned with the COLR override subscriptionoption and the MS is registered in the HPLMN country;otherwise shall be absent.
COLR provision C Indicates that COLR is provisioned. Shall be present for anMT call if COLR is provisioned; otherwise shall be absent.
No Reply Condition Timer C Value of timer to be used to determine the No subscriberreply condition. Shall be present for an MT call if the CallForwarding on No Reply service is active and operative;otherwise shall be absent.
CUG index C For the definition of this IE, see [11]. May be present (as anetwork operator option) for an ordinary MO call if the callis a CUG call; shall be present for an MT call if the call is aCUG call; otherwise shall be absent.
CUG interlock C For the definition of this IE, see [11]. Shall be present foran ordinary MO call if the call is a CUG call; otherwise shallbe absent.
CUG outgoing access C For the definition of this IE, see [11]. Shall be present foran ordinary MO call if the call is a CUG call with outgoingaccess; otherwise shall be absent.
Advice of Charge provision C Indicates whether Advice of Charge (Information) or Adviceof Charge (Charging) is provisioned. Shall be present foran ordinary MO call or an MT call if Advice of Charge isprovisioned; otherwise shall be absent.
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8.1.8 Complete Call ack
This message contains no information elements.
8.1.9 Complete Call negative response
The negative response information element can take the following values:
- Absent subsccriber;- Busy subscriber;- No subscriber reply;- Radio congestion.
8.1.10 Forward New TMSI
The following information element is required:
Information element name Required DescriptionTMSI M TMSI to be sent to the MS.
8.1.11 Forward New TMSI ack
This message contains no information elements.
8.1.12 Forward New TMSI negative response
The negative response information element can take the following value:
- TMSI reallocation failure.
8.1.13 Obtain Subscriber Info
The following information elements are required:
Information element name Required DescriptionIMSI M IMSI of the MS for which information is required.Location informationrequested
C Indicates that the VLR requires location information for theMS. Shall be present if location information is required;otherwise shall be absent.
Subscriber state requested C Indicates that the VLR requires state information for theMS. Shall be present if state information is required;otherwise shall be absent.
8.1.14 Obtain Subscriber Info ack
The following information elements are required:
Information element name Required DescriptionCell global identity C Identity of the cell from which the MS established a radio
transaction. Shall be present if the VLR requested locationinformation and the mobile is currently engaged on a radiotransaction; otherwise shall be absent.
Age of location information C Time in minutes since the MS last established a radiotransaction. Shall be present if the VLR requested locationinformation; otherwise shall be absent.
Subscriber state C Indicates whether the MS is busy (i.e. engaged on a circuit-switched call) or assumed idle. Shall be present if the VLRrequested state information; otherwise shall be absent.
8.1.15 Page MS
The following information elements are required:
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Information element name Required DescriptionIMSI M IMSI of the MS to be paged.Location area ID M Location area in which the MS is to be paged.Page type M Indicates whether the paging is for a circuit-switched call,
MT SMS delivery or SS activityTMSI O TMSI to be broadcast to identify the MS.
8.1.16 Page MS negative response
The negative response information element can take the following values:
- Absent subscriber;- Busy subscriber (More calls possible);- Busy subscriber (NDUB);- System failure;- Unknown location area ID.
The Page MS negative response Busy subscriber (More calls possible) also indicates the basic servicewhich applies for the established call.
8.1.17 Process Access Request
The following information elements are required:
Information element name Required DescriptionCM service type M Indicates the type of access required: normal MO call,
emergency call or page response. Other values (shortmessage service and SS request) defined for this IE arenot considered in this specification.
Access connection status M Indicates whether or not the connection to the MS isciphered and whether or not it is authenticated.
Current location area ID M Identity of the location area from which the access requestwas received.
IMSI C IMSI of the MS requesting the access. For normal MO callor page response, one of IMSI or TMSI shall be present.For emergency call, one of IMSI, TMSI or IMEI shall bepresent.
TMSI C TMSI of the MS requesting the access. For normal MO callor page response, one of IMSI or TMSI shall be present.For emergency call, one of IMSI, TMSI or IMEI shall bepresent.
IMEI C IMEI of the MS requesting the access. For normal MO callor page response, one of IMSI or TMSI shall be present.For emergency call, one of IMSI, TMSI or IMEI shall bepresent.
CKSN C Cipher key sequence number of the MS requesting theaccess. Shall be present if TMSI is present; otherwise shallbe absent.
8.1.18 Process Access Request ack
The following information elements are required:
Information element name Required DescriptionIMSI C IMSI of the MS requesting the access. For normal MO call
or page response, shall be present. For emergency call,one of IMSI or IMEI shall be present.
IMEI C IMEI of the MS requesting the access. For normal MO callor page response, shall be absent. For emergency call,one of IMSI or IMEI shall be present.
MSISDN O MSISDN of the MS requesting the access.
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8.1.19 Process Access Request negative response
The negative response information element can take the following values:
- Roaming not allowed;- System failure;- Unidentified subscriber;- Illegal equipment;- Illegal subscriber.
8.1.20 Process Call Waiting
The following information elements are required:
Information element name Required DescriptionMSISDN M MSISDN of the MS for which the Process Call Waiting is
sent.GSM bearer capability C Shall be present if it was received in the Provide Roaming
Number for the waiting call; otherwise shall be absent.ISDN bearer capability C Shall be present if it was received in the Provide Roaming
Number for the waiting call; otherwise shall be absent.ISDN low layer compatibility C Shall be present if it was received in the Provide Roaming
Number for the waiting call; otherwise shall be absent.ISDN high layer compatibility C Shall be present if it was received in the Provide Roaming
Number for the waiting call; otherwise shall be absent.CLIP provision C Indicates that CLIP is provisioned. Shall be present if CLIP
is provisioned; otherwise shall be absent.CLIR override provision C Indicates that the CLIR override subscription option of
CLIP is provisioned. Shall be present if CLIP is provisionedwith the CLIR override subscription option and the MS isregistered in the HPLMN country; otherwise shall beabsent.
COLR provision C Indicates that COLR is provisioned. Shall be present ifCOLR is provisioned; otherwise shall be absent.
No Reply Condition Timer C Value of timer to be used to determine the No subscriberreply condition. Shall be present if the Call Forwarding onNo Reply service is active and operative; otherwise shallbe absent.
CUG index C For the definition of this IE, see [11]. Shall be present if thewaiting call is a CUG call; otherwise shall be absent.
Advice of Charge provision C Indicates whether Advice of Charge (Information) or Adviceof Charge (Charging) is provisioned. Shall be present ifAdvice of Charge is provisioned; otherwise shall be absent.
8.1.21 Process Call Waiting ack
This message contains no information elements.
8.1.22 Process Call Waiting negative response
The negative response information element can take the following values:
- Busy subscriber;- No subscriber reply.
8.1.23 Provide IMEI
This message contains no information elements.
8.1.24 Provide IMEI ack
The following information element is required:
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Information element name Required DescriptionIMEI M IMEI of the ME involved in the access request.
8.1.25 Provide IMSI
This message contains no information elements.
8.1.26 Provide IMSI ack
The following information element is required:
Information element name Required DescriptionIMSI M IMSI of the MS involved in the access request.
8.1.27 Search For MS
The following information elements are required:
Information element name Required DescriptionIMSI M IMSI of the MS to be paged in all location areas.Page type M Indicates whether the paging is for a circuit-switched call,
MT SMS delivery or SS activityTMSI O TMSI to be broadcast to identify the MS.
8.1.28 Search For MS ack
The following information element is required:
Information element name Required DescriptionLocation area ID M Location area in which the MS responded to the page.
8.1.29 Search For MS negative response
The negative response information element can take the following values:
- Absent subscriber;- Busy subscriber (More calls possible);- Busy subscriber (NDUB);- System failure.
The Search For MS negative response Busy subscriber (More calls possible) also indicates the basicservice which applies for the established call.
8.1.30 Send Info For Incoming Call
The following information elements are required:
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Information element name Required DescriptionMSRN M Mobile Station Roaming Number received in the IAM.Bearer service C GSM bearer service required for the MT call. Shall be
present if the MSC was able to derive a GSM bearerservice from ISDN BC/LLC/HLC information received in theIAM; otherwise shall be absent.
Teleservice C GSM teleservice required for the MT call. Shall be presentif the MSC was able to derive a GSM teleservice fromISDN BC/LLC/HLC information received in the IAM;otherwise shall be absent.
Dialled number C Number dialled by the calling subscriber. Shall be presentif it was received in the IAM; otherwise shall be absent.
Number of forwarding C Number of times the incoming call has already beenforwarded. Shall be present if it was received in the IAM;otherwise shall be absent.
CUG interlock C For the definition of this IE, see [11]. Shall be present if itwas received in the IAM; otherwise shall be absent.
CUG outgoing access C For the definition of this IE, see [11]. Shall be present if itwas received in the IAM; otherwise shall be absent.
8.1.31 Send Info For Incoming Call ack
The following information elements are required:
Information element name Required DescriptionIMSI M IMSI of the B subscriber.Forwarded-to number M E.164 number of the C subscriber.Forwarding reason M Indication of why the call has been forwarded (on mobile
subscriber busy, on mobile subscriber not reachable or onno subscriber reply).
Notification to calling party M Indication of whether the calling party is to be notified thatthe call has been forwarded.
Notification to forwardingparty
C Indication of whether the forwarding party is to be notifiedthat the call has been forwarded. Shall be present if the callis to be forwarded on mobile subscriber busy or on nosubscriber reply; otherwise shall be absent.
Forwarded-to subaddress C Subaddress of the C subscriber (see [2]). Shall be presentif a forwarded-to subaddress is stored in the VLR inassociation with the forwarded-to number; otherwise shallbe absent.
CUG interlock C For the definition of this IE, see [11]. Shall be present if theVLR has determined that the forwarded call is to be treatedas a CUG call in accordance with the rules in [11],otherwise shall be absent.
CUG outgoing access C For the definition of this IE, see [11]. Shall be present if theVLR has determined that the forwarded call is to be treatedas a CUG call with outgoing access in accordance with therules in [11], otherwise shall be absent.
8.1.32 Send Info For Incoming Call negative response
The negative response information element can take the following values:
- Absent subscriber;- Busy subscriber;- CUG reject (Called party SS interaction violation);- Forwarding violation;- Impossible call completion;- No subscriber reply;- System failure;- Unallocated roaming number;
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8.1.33 Send Info For Outgoing Call
The following information elements are required:
Information element name Required DescriptionCalled number M E.164 number of the call destination.Bearer service C Bearer service required for the MO call, derived from the
GSM bearer capability information received in the setuprequest from the MS. One of bearer service or teleserviceshall be present.
Teleservice C Teleservice required for the MO call, derived from the GSMbearer capability information received in the setup requestfrom the MS or from the emergency setup request from theMS. One of bearer service or teleservice shall be present.
CUG index C For the definition of this IE, see [11]. Shall be present if itwas received in the setup request from the MS.
Suppress preferential CUG C For the definition of this IE, see [11]. Shall be present if itwas received in the setup request from the MS.
Suppress CUG outgoingaccess
C For the definition of this IE, see [11]. Shall be present if itwas received in the setup request from the MS.
8.1.34 Send Info For Outgoing Call negative response
The negative response information element can take the following values:
- Bearer service not provisioned;- Call barred (Operator determined barring);- Call barred (Supplementary service barring);- CUG reject (Inconsistent access information - index incompatible with basic service);- CUG reject (Inconsistent access information - no CUG selected);- CUG reject (Outgoing calls barred within the CUG);- CUG reject (Unknown CUG index);- Teleservice not provisioned.
8.1.35 Set ciphering mode
The following information element is required:
Information element name Required DescriptionCiphering mode M Indicates whether ciphering of the radio connection is
required, and if so which ciphering algorithm is to be used.Kc C Ciphering key to be used if ciphering of the radio
connection is required. Shall be present if the cipheringmode indicates that ciphering of the radio connection isrequired, otherwise shall be absent.
8.1.36 Trace subscriber activity
The following information elements are required:
Information element name Required DescriptionTrace reference M Reference number to be included with tracing reports
which the MSC sends to the OMCTrace type M For the definition of this IE, see [20]
8.1.37 Use existing TMSI
This message contains no information elements.
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8.2 Messages on the C interface (MSC-HLR)
8.2.1 Send Routeing Info
The following information elements are required:
Information element name Required DescriptionMSISDN M MSISDN of the B subscriber (see [2]).CUG interlock C For the definition of this IE, see [11]. Shall be present if the
GMSC received it in the IAM, otherwise shall be absent.CUG outgoing access C For the definition of this IE, see [11]. Shall be present if the
GMSC received it in the IAM, otherwise shall be absent.Number of forwarding C Number of times the incoming call has already been
forwarded. Shall be present if it was received in the IAM;otherwise shall be absent.
ISDN BC C ISDN bearer capability. Shall be present if the GMSCreceived it in the IAM, otherwise shall be absent.
ISDN LLC C ISDN lower layer compatibility. Shall be present if theGMSC received it in the IAM, otherwise shall be absent.
ISDN HLC C ISDN higher layer compatibility. Shall be present if theGMSC received it in the IAM, otherwise shall be absent.
8.2.2 Send Routeing Info ack
The following information elements are required:
Information element name Required DescriptionIMSI M IMSI of the B subscriber (see [2]).Roaming number C E.164 number required to route the call to VMSCB (see
[2]). Shall be present if the HLR received it in the ProvideRoaming Number ack, otherwise shall be absent.
Forwarded-to number C E.164 number of the C subscriber. Shall be present if theHLR has determined that the call is to be forwarded,otherwise shall be absent.
Forwarded-to subaddress C Subaddress of the C subscriber (see [2]). Shall be presentif the HLR has determined that the call is to be forwardedand a forwarded-to subaddress is stored in the HLR inassociation with the forwarded-to number, otherwise shallbe absent.
Notification to calling party C Indication of whether the calling party is to be notified thatthe call has been forwarded. Shall be present if the HLRhas determined that the call is to be forwarded, otherwiseshall be absent.
Forwarding reason C Indication of why the call has been forwarded(unconditionally or on mobile subscriber not reachable).Shall be present if the HLR has determined that the call isto be forwarded, otherwise shall be absent.
CUG interlock C For the definition of this IE, see [11]. Shall be present if theHLR has determined that the call is to be treated as a CUGcall in accordance with the rules in [11], otherwise shall beabsent.
CUG outgoing access C For the definition of this IE, see [11]. Shall be present if theHLR has determined that the call is to be treated as a CUGcall with outgoing access in accordance with the rules in[11], otherwise shall be absent.
8.2.3 Send Routeing Info negative response
The negative response information element can take the following values:
- Absent subscriber;- Bearer service not provisioned;- Call barred (Operator determined barring);
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- Call barred (Supplementary service barring);- CUG reject (Called party SS interaction violation);- CUG reject (Incoming calls barred within CUG);- CUG reject (Requested basic service violates CUG constraints);- CUG reject (Subscriber not member of CUG);- Data missing;- Facility not supported;- Forwarding violation- Number changed;- System Failure;- Teleservice not provisioned;- Unexpected data value;- Unknown subscriber.
8.3 Messages on the D interface (VLR-HLR)
8.3.1 Provide Roaming Number
The following information elements are required:
Information element name Required DescriptionIMSI M IMSI of the B subscriber (see [2]).MSC number M E.164 number which identifies VMSCB (see [2]).MSISDN O E.164 number which identifies the B subscriber. May be
present if the HLR requires it to be included in the call datarecord.
LMSI C Local Mobile Subscriber Identity. Shall be present if theLMSI was sent to HLRB at location updating.
GSM bearer capability C Information to define the GSM bearer capability requiredfor the call. For alternate speech/fax, alternate speech/dataor speech followed by data calls this information elementshall contain two GSM bearer capabilities, as specified inGSM 04.08. May be present if the HLR can determine therequired GSM bearer capability from ISDN compatibilityinformation received in the Send Routeing Info message,or from the MSISDN if a multi-numbering scheme is used;otherwise shall be absent. If the ISDN BC and ISDN LLCIEs are present, the GSM bearer capability IE shall beabsent.
ISDN BC C ISDN bearer capability. May be present if the HLR receivedit in the Send Routeing Info message, otherwise shall beabsent. If the GSM bearer capability IE is present, theISDN BC IE shall be absent.
ISDN LLC C ISDN lower layer compatibility. May be present if the HLRreceived it in the Send Routeing Info message, otherwiseshall be absent. If the GSM bearer capability IE is present,the ISDN LLC IE shall be absent.
ISDN HLC C ISDN higher layer compatibility. Shall be present if the HLRreceived it in the Send Routeing Info message, otherwiseshall be absent.
8.3.2 Provide Roaming Number ack
The following information element is required:
Information element name Required DescriptionRoaming number M E.164 number required to route the call to VMSCB (see
[2]).
8.3.3 Provide Roaming Number negative response
The negative response information element can take the following values:
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- Absent subscriber;- Data missing;- Facility not supported;- No roaming number available;- OR not allowed;- Unexpected data value.
8.3.4 Provide Subscriber Info
The following information elements are required:
Information element name Required DescriptionIMSI M IMSI of the subscriber for whom information is requested
(see [2]).LMSI C Local Mobile Subscriber Identity. Shall be present if the
LMSI was sent to the HLR at location updating.Requested information M Indicates whether the HLR requires location information,
subscriber state or both location information andsubscriber state.
8.3.5 Provide Subscriber Info ack
The following information elements are required:
Information element name Required DescriptionLocation information C Information to define the location of the MS: see definition
in subclause 8.3.5.1. Shall be present if locationinformation was requested and is available; otherwise shallbe absent.
Subscriber state C Indicates whether the MS is busy (i.e. engaged on a circuit-switched call), network determined not reachable (IMSIdetached or roaming in a prohibited location area) orassumed idle. Shall be present if subscriber state wasrequested; otherwise shall be absent.
8.3.5.1 Location information
The compound information element Location information consists of the following subordinate informationelements:
Information element name Required DescriptionLocation number C For a definition of this information element, see [21]. Shall
be present if the VLR can derive it from the stored cellglobal identity or location area identity; otherwise shall beabsent.
Cell ID C Cell global identity of the cell in which the MS lastestablished a radio transaction. Shall be present if theMSC/VLR can supply it; otherwise shall be absent. Shall beabsent if Location area ID is present.
Location area ID C Identity of the location area in which the MS lastestablished a radio transaction. Shall be present if theMSC/VLR can supply it; otherwise shall be absent. Shall beabsent if Cell ID is present.
Geographical information C For a definition of this information element, see [4]. Shallbe present if the VLR can derive it from the stored cellglobal identity or location area identity; otherwise shall beabsent.
VLR number M E.164 number which identifies the VLR (see [2]).Age of location information M Measured in minutes.
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8.3.6 Provide Subscriber Info negative response
The negative response information element can take the following values:
- Unexpected data value.
8.3.7 Restore Data
The following information elements are required:
Information element name Required DescriptionIMSI M IMSI of the subscriber for whom data are to be restored
(see [2]).LMSI O LMSI of the subscriber for whom data are to be restored
(see [2]). May be included if required by the requestingVLR.
8.3.8 Restore Data ack
The following information elements are required:
Information element name Required DescriptionHLR number M E.164 number which identifies the HLR (see [2]).MS not reachable flag C Indicates whether the VLR should notify the HLR when the
MS next establishes radio contact. Shall be present if thecorresponding indicator is set in the HLR record for thesubscriber; otherwise shall be absent.
8.3.9 Restore Data negative response
The negative response information element can take the following values:
- System failure;- Unknown subscriber.
8.3.10 Provide Subscriber Info negative response
The negative response information element can take the following values:
- Data missing;- Unexpected data value.
8.4 Messages on the F interface (MSC-EIR)
8.4.1 Check IMEI
The following information element is required:
Information element name Required DescriptionIMEI M IMEI of the ME whose status is to be checked (see [2]).
8.4.2 Check IMEI ack
The following information element is required:
Information element name Required DescriptionEquipment status M Indicates whether the ME is black-listed, grey-listed or
white-listed
8.4.3 Check IMEI negative response
The negative response information element can take the following value:
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- Unknown equipment.
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Annex A (Informative) Handling of an IAM at an MSC
An MSC which receives an IAM from an originating exchange may react in three different ways:
- It acts as a transit exchange, i.e. it relays the IAM to a destination exchange determined by analysisof the called party address, and thereafter relays other telephony signalling between the originatingand destination exchange until the connection is released. This behaviour is not specific to GSM;
- It acts as a terminating exchange, i.e. it attempts to connect the call to an MS currently registered inthe service area of the MSC;
- It acts as a GMSC, i.e. it interrogates an HLR for information to route the call. If the HLR returnsrouteing information, the MSC uses the routeing information from the HLR to construct an IAM,which it sends to a destination exchange determined by analysis of the routeing information fromthe HLR.
Sheet 1: when the MSC coordinating process has decided whether the MSC is to act as a terminatingVMSC, a GMSC or a transit exchange, it forwards the IAM to an idle instance of the appropriate process.
Sheet 2: after the MSC coordinating process has sent an IAM to an instance of the process MT_GMSC orICH_MSC, it acts as a transparent relay for messages received from the originating exchange and theprocess instance (denoted by ‘offspring’). After the MSC coordinating process has relayed a Releasemessage, it returns to the idle state.
Sheet 2: after the MSC coordinating process has sent an IAM to a destination exchange, it acts as atransparent relay for messages received from the originating exchange and the destination exchange.After the MSC coordinating process has relayed a Release message, it returns to the idle state.
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Process in the MSC tohandle an incoming IAMand trigger the correct application process
Process MSC_Coord Coord_M1(2)
IDLE
InitialAddress
From originatingexchange
Called party address in MSRN rangefor this MSC?
HLR addressderivable?
InitialAddress
To processMT_GMSC
Relay_Information_
Internally
InitialAddress
To destinationdetermined byrouteing tables
Relay_Information_
Externally
InitialAddress
To processICH_MSC
No
Yes
No
Yes
Figure 63a: Process MSC_Coord (sheet 1)
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Process in the MSC tohandle an incoming IAMand trigger the correct application process
Process MSC_Coord Coord_M2(2)
Relay_Information_
Internally
ReleaseFrom originatingexchange
Release To offspring
IDLE
Release From offspring
ReleaseTo originatingexchange
IDLE*From originatingexchange
- To offspring
Relay_Information_
Internally
* From offspring
-To originatingexchange
Relay_Information_
Internally
Relay_Information_
Externally
ReleaseFrom originatingexchange
ReleaseTodestinationexchange
IDLE
ReleaseFromdestinationexchange
ReleaseTo originatingexchange
IDLE*From originatingexchange
-Todestinationexchange
Relay_Information_
Externally
*From destinationexchange
-To originatingexchange
Relay_Information_
Externally
Figure 63b: Process MSC_Coord (sheet 2)
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History
Document history
Date Status Comment
January 1997 Proposed version 2.1.0 Presented to SMG3, Dresden