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HUAWEI CCS7 Signaling System

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HUAWEI

Chapter 1 SCCP Chapter 2 TCAP Chapter 3 INAP

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HUAWEI

SCCP: Signaling Connection Control Part

Chapter 1 SCCPChapter 1 SCCP

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HUAWEI Where is SCCP?

INAP: IN Application Protocol MAP: Mobile Application PartCAP: CAMEL Application Part TCAP: Transaction Capability Application PartTUP: Telephone User Part ISUP: ISDN User PartMTP: Message Transfer Part SCCP: Signaling Connection Control Part

TUP ISUP TCAP

INAP CAP MAP

MTP

SCCP

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HUAWEI What is SCCP?

In No.7 signaling system ， SCCP and MTP layer three together are responsible for signaling network layer function. SCCP expends the MPT functions in the following points:

Enable to convey various non-circuit-related signaling message.

Provide enhanced addressing and routing function, and enable to achieve the direct global transmission between different CCS7 networks by using GT addressing.

Expend the user part of MTP. SCCP supports up to 256 kinds of sub systems in stead of 16 in MTP.

Enable to provide connectionless service and connection-oriented service.

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HUAWEI Service Functions of SCCP Network

According to the various service requirement needed by user, the SCCP provides four classes of service: two for connectionless services and two for connection-oriented services. The four classes are:

Class 0: Basic connectionless class.

Class 1: In-sequence delivery connectionless class.

Class 2: Basic connection-oriented class.

Class 3: Flow control connection-oriented class.

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HUAWEI Addressing and Routing Functions of SCCP

The SCCP routing provides a powerful address translation function, which requires for connectionless and connection-oriented service. The SCCP routing provides a powerful addressing information translation function on behalf of its users. The routing function also responds to the MTP and SCCP congestion reports.

Addressing within the SCCP of CCS7 makes use of three separate elements:

DPC;

Global Title (GT);

Sub-System Number (SSN);

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HUAWEI Primitive

In CCS7 system, the information exchange between two adjacent layers is called primitive which includes primitive name, primitive type and primitive parameters. There are four types of primitives:

Request Indication Response Confirmation

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HUAWEI Primitives between SCCP and SCCP-User

Primitives between SCCP and SCCP-User (TCAP) are N_Primitives. The connectionless services use the following N_Primitives:

N_UNITDATA_REQ ： is used when SCCP-User requires SCCP to send data.

N_UNITDATA_IND ： is used when SCCP reports the received data to SCCP-User.

N_NOTICE_IND ： is used when SCCP reports the reason why the SCCP-User data cannot be sent to peer point.

N-Primitives can be traced on SSP maintenance terminal.

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HUAWEI N_UNITDATA Parameters

N-UNITDATA_IND and N-UNITDATA_REQ have the same parameters.

SCCP-USER Octet (83H)

Routing Label (DPC 、 OPC 、 SLS)

Sequence Control (SLS)

Protocol Class (81H)

Parameter Location Pointer (Called Address, Caller Address, User Data Pointer)

Called Address (Destination Address)

Caller Address (Source Address)

User Data (SCCP-User Data to be sent by SCCP transparently, SCCP makes no change to them)

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HUAWEI

N_NOTICE has the same parameter structure with N_UNITDATA, but the Protocol Class is changed to return reason.

N_NOTICE Parameters

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HUAWEI SCCP Message Types

Message is the information exchanged by the same layers in two signaling points.

There are 17 kinds of SCCP messages. Among them UDT (Unit Data) and UDTS (Unit Data Service) are used for connectionless services. The codes for UDT and UDTS are 09H and 0AH.

INAP only uses UDT messages

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HUAWEI

TCAP: Transaction Capability Application Part

Chapter 2 TCAPChapter 2 TCAP

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HUAWEI Applications of TCAP

Applications of TCAP:

Data Exchange between switching systems

Switching systems access network database center

Network databases establish remote operation dialogue

Examples of TCAP applications:

Mobile service applications

Free phone service (800-service)

Credit Card calling

Operation & Maintenance applications

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HUAWEI Dialogue

Dialogue is the association established between two TC -users exchanging data. Whenever two signaling points are going to exchange data, they will setup a dialogue via TCAP. It is TCAP that initiates, maintains and releases of a dialogue. But TCAP does not care the functions of the dialogue.

The procedure of message exchange between two signaling points is similar to man-machine dialogue mode, which involves all necessary messages such as BEGIN and END.

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HUAWEI Component

Component is the protocol data unit exchanged between TC –users. i.e. the information exchanged in a dialogue is just a set components.

Components are defined by TC-Users. Components include the invoke operation by initiator and the returned result of the operation. The operation is decided by applications, e.g. number translation.

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HUAWEI

A dialogue has one or more components. A service procedure is just one dialogue. i.e. all the operations of a service procedure buildup a dialogue, the dialogue is the carrier of the operations.

The Relationship Between Dialogue and Component

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HUAWEI Categories of TCAP Components

Invoke（ INV） is used to send an operation request to remote TC-User.

Return Result-Last（ RR-L） is used to return the components of final result of last INV operation.

Return Result-not Last（ RR-NL） is used to return the components of non-final result of last INV operation.

Return Error（ RE） is used to return the components of error information, in which an error code is embedded

Reject（ RJ）： is used to reject last INV operation, in which a problem code is embedded.

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HUAWEI

According to different requirements of operation results, TCAP are classified into 4 classes:

Class 1: Result will be returned no matter the operation is successful or not. i.e. a RR-L, RR-NL or RE must be returned.

Class 2: Only when the operation fails, a RE will be returned.

Class 3: Only when the operation succeeds, a RR-L or RR-NL will be returned.

Class 4: No result returned no matter the operation is successful or not.

Classes of TCAP Operations

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HUAWEI

TCAP and TC-User exchange data via TC_Primitives.

There are 16 kinds of TC_Primitives, among them there 9 Component TC-Primitives which are related to components and 7 Dialogue TC-Primitives which are related to dialogues.

The TC_Primitives from TCAP to TC-User are Indication primitives, from TC-User to TCAP are Request primitives.

TC Primitives

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HUAWEI Component TC_Primitives (1)

TC－ INVOKE is used to invoke an operation.

TC－ RESULT－ L is used to return the result of an operation.

TC－ RESULT－ NL is similar to TC － RESULT － L, but only returns the middle result.

Note: all above primitives have both Indication and Request types.

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HUAWEI

TC－ U－ ERROR is a Request Primitive which is used to return the error code when the operation fails although TC-User has received the correct operation request.

TC－ U－ REJECT ： is a Request Primitive which is used to return reject code when TC-User has received an incorrect operation request.

TC－ U－ CANCEL is a Request Primitive which is used for TC-User to request TCAP to cancel an operation.

Component TC_Primitives (2)

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HUAWEI

TC－ L－ CANEL is an Indication Primitive which is used to notify TC-User an operation is overtime.

TC－ L－ REJECT is an Indication Primitive which is used to reject an operation by local TCAP.

TC－ R－ REJECT ： is an Indication Primitive which is used to reject an operation when remote TCAP rejects the operation.

Component TC_Primitives (3)

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HUAWEI Types of TCAP Dialogues

There are two types of TCAP dialogues.

Unstructured Dialogue in which only unidirectional (UNI) messages are included. No response to be returned from opposite point in unstructured dialogue (e.g. a dialogue for sending an alarm message). Intelligent Network seldom uses this kind of dialogues.

Structured Dialogue has initiating, maintaining and ending processes. It has BEGIN, CONTINUE and END or ABORT messages. Intelligent Network just uses this kind of dialogues.

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HUAWEI

TC-UNI TC-User or TCAP request to begin a UNI dialogue.

TC－ BEGIN Request or indicate to begin a dialogue.

TC－ CONTINUE Request or indicate to maintain a dialogue.

TC－ END Request or indicate to end a dialogue.

Dialogue TC_Primitives (1)

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HUAWEI

TC－ U－ ABORT ： Request to abort a dialogue.

TC－ P－ ABORT ： Indicate TC-User to abort a dialogue because of the error in transaction layer.

TC－ NOTICE ： Indicate TC-User that the network service provider cannot provide the required service (e.g. STP does not support INAP).

Dialogue TC_Primitives (2)

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HUAWEI An Example of TCAP Process

TC-BeginTC-Invoke (Invoke)

TC-ContinueTC-Invoke (Invoke)

TC-Continue

TC-Result-L (RR-L)

TC-End

TC-Result-L (RR-L)

Node1 (SSP) Node2 (SCP)

SSP begins a dialogue to query the balance of a calling card subscriber.

SCP asks SSP to return the password.

SSP returns the password.

SCP returns balance of the subscriber.

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HUAWEI

INAP: Intelligent Network Application Part

Chapter 3 INAPChapter 3 INAP

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HUAWEI The Functions of INAP

INAP defines operation criterion among the IN functional entities SSF, SCF, SRF and SDF.

INAP is transmitted by SCCP UDT data, using connectionless services.

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HUAWEI The Relationship Between INAP and SCCP

INAP usually uses DPC+SSN routing mode of SCCP.

INAP can also use GT routing mode of SCCP.

INAP uses class 0 and class 1 connectionless services of SCCP.

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HUAWEI INAP Operation Categories

Class 1: Result will be returned no matter the operation is successful or not. i.e. a RR-L, RR-NL or RE must be returned.Class 2: Only when the operation fails, a RE will be returned.Class 3: Only when the operation succeeds, a RR-L or RR-NL will be returned.Class 4: No result returned no matter the operation is successful or not.

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HUAWEI

INAP is a kind of TC-User.

In INAP protocol, all INAP operations are also classified into 4 classes.

Class 1 Activate Service Filtering, P&C

Class 2 Initial DP, RRBE

Class 3 AT

Class 4 RC, BER

INAP Operations

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HUAWEI IDP: Initial DP

IDP is the first INAP message sent from SSP to SCP, requesting SCP to establish the control relationship for an IN call. The parameters included in IDP are: access code, service key (the unique identifier of an IN service), caller number, called number, number attributes, etc.

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HUAWEI RRBE: Request Report BCSM Event

RRBE is sent from SCP to SSP, requesting SSP to configure DP dynamically. When SSP meets these DPs in later call process, SSP will report call information to SCP. RRBE provides SCP the condition of controlling calls.The parameters of RRBE include DP type, DP condition, etc. One RRBE can configure several DPs.

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HUAWEI CTR: Connect To Resource

CTR is sent from SCP to SSP, requesting SSP to connect the user to IP. CTR provides the users the condition of using IP.If IP is integrated with SSP, SSP makes only the internal connection with IP. If IP is independent from SSP, SSP communicates IP via TUP messages, connecting the users to IP through PSTN voice channels.

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HUAWEIP&C: Prompt & Collect User Information

P&C is sent from SCP to SSP, requesting IP to play voice prompts the users and collect the users’ input.

P&C needs IP to return operation results.

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HUAWEI DFC: Disconnect Forward Connect

DFC is sent from SCP to SSP, requesting SSP to disconnect the connection between the users and IP.

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HUAWEI AC: Apply Charging

AC is sent from SCP to SSP, requesting SSP to charge the call.

The parameters of AC include: charge class, the balance of the subscriber, charging party, etc.

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HUAWEIConnect：

Connect is sent from SCP to SSP, requesting SSP to connect the users to the designated number.

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HUAWEI ACR: Apply Charging Report

ACR is sent from SSP to SCP, reporting the charge result.The parameters in ACR include: the call start time, call end time, call length, caller number, called number, charging number, fee, etc.

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HUAWEI ERB: Event Report BCSM

ERB is sent from SSP to SCP when SSP detects the DPs configured by SCP in last RRBE message, reporting the call information to SCP.

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HUAWEI RC: Release Call

RC is sent from SCP to SSP, requesting SSP to release the occupied IN call resources.

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HUAWEIPA: Play announcement

PA is sent from SCP to SSP, requesting IP to play voice prompts to the users.

PA does not need result return from IP.

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HUAWEI SRR: Specialized Resource Report

SRR is sent from SSP to SCP, notifying SCP the end of playing announcement.

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HUAWEI AT: Activity Test

SCP sends AT to SSP every 6 minutes when the call is established to check the communication between SSP and SCP. If SSP can return AT_ack, the communication is good. If no AT_ack returns to SCP, the communication is broken, and SCP will release the resources occupied this IN call.

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HUAWEI

Initial DPRequest Report BCSM Event

Apply Charging

Apply Charging ReportBCSM Event ReportRelease Call

Connect

SSP SCP

An Example of INAP (FPH Service)

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HUAWEI An Example of INAP (Continue)

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HUAWEI SCCP 、 TCAP and INAP (FPH Service)

AP: Application Process, which processes IN calls in SSP.

InitialDP

Request Report Bcsm Event

Apply Charging

Connect

Apply Charging Report

Event Report BCSM

Release Call

AP

TC-BEGIN-REQ

TC-INVOKE-REQ

TC-CONTINUE-IND

TC-INVOKE-IND

TC-CONTINUE-IND

TC-INVOKE-IND

TC-CONTINUE-IND

TC-INVOKE-IND

TC-CONTINUE-REQ

TC-INVOKE-REQ

TC-CONTINUE-REQ

TC-INVOKE-REQ

TC-END-IND

TC-INVOKE-IND

TCAP

N_UNITDATA-REQ

N_UNITDATA-IND

N_UNITDATA-IND

N_UNITDATA-IND

N_UNITDATA-REQ

N_UNITDATA-REQ

N_UNITDATA-IND

UDT

UDT

UDT

UDT

UDT

UDT

UDT

MSU

MSU

MSU

MSU

MSU

MSU

MSU

SCCP MTP SCPINAP