Administration of Routes in MD110

OPERATIONAL DIRECTIONS114/154 31-APD 101 02 Uen K

Administration of routes

Contents

1 General

1 General 1.1 Introduction 1.2 Acronyms 2

Definitions and terminology

3

Basic signalling

3.1 CAS and CCS 3.2 Line and register signalling 3.3 Example of signalling 4

Prerequisites

5

Aids

6

References

7

Execution

7.1 Routing, general7.2 Routing, CCSS77.3 Basic routing 7.4 Extended services for outgoing traffic7.5 A-number request from PSTN7.6 A-subscriber charging 7.7 DISA - Direct Inward System Access7.8 DRA - Dynamic Route Allocation7.9 ERWT - Expensive Route Warning Tone7.10 IDNX Interworking 7.11 LCR - Least Cost Routing 7.12 Loop avoidance/Transit counter7.13 MCT - Malicious call tracing 7.14 PNR - Private network routing7.15 Semipermanent connections with D over B signalling 8

Termination

of 63Administration of routes

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1.1 Introduction These operational directions give a concise, summarized overview description of the administration of routes. The same, and more detailed, information can be found in the different operational directions in the section References.

The first part of the document consists of definitions and explanations of the used terminology. The second part explains the fundamentals of signalling and routing. The last part explains how to organize and set up routes, and special route applications in general.

External lines are used to connect an ASB 501 exchange with other exchanges, both private (PABX) and public exchanges. External lines with identical characteristics, signalling and direction together form a route.

This document deals with both digital and analogue external lines. It also mentions different ways of signalling over an external line. Signalling is the way the exchanges communicate with each other.

1.2 Acronyms

APNSS Analogue Private Network Signalling System AS Application System CAS Channel Associated Signalling CCITT Comite Consultatif International Telegraphique et Telephonique

(Now called International Telecommunication Union, Telecommunication Standardization Sector, ITU-T)

CCS Common Channel Signalling CCSS7 Common Channel Signalling System No. 7 DID Direct In Dialling DPNSS Digital Private Network Signalling System DRA Dynamic Route Allocation DSS1 Digital Signalling System 1 EA External Analysis ELU Extension Line Unit ELU32 Extension Line Unit for H.323 interface, used for both extensions and trunks. Is replaced

by IPLU for new sales. IP Internet Protocol IPLU Internet Protocol Line Unit for H.323 interface, used for both extensions and trunks ISDN Integrated Services Digital Network IVN Intervening Network LAC Least Cost Routing Access Code LCR Least Cost Routing LIM Line Interface Module MDP Market Dependent Parameter MOS Message Oriented Signalling MTP Message Transfer Part OPI PABX Operator Instrument



2 Definitions and terminology Alternative routing

By alternative routing it is possible to reach an external destination via different routes. A primary choice route can have several alternative routes to reach the external destination.

If the primary route is not available, the system tries to use the first alternative route and so on. If necessary the system will modify the dialled number (add predigits and/or delete dialled digits) to suite the number to the numbering plan used in the exchange at the other end of the alternative route.

APNSS - Analogue Private Network Signalling System

APNSS is a signalling system similar to DPNSS. Both systems uses CCS and the same signalling protocol. The main differences are that APNSS uses analogue external lines and that one external line is used as signalling channel using modem.

APNSS is a cost effective way to get the features of DPNSS if there already exist analogue lines. Instead of leasing/building expensive PCM lines needed for DPNSS, APNSS can utilize the existing analogue lines to get the netservices of DPNSS.

B-Channel

A 64 kbit/s channel is used in ISDN for transmitting digitally coded speech and data. It is used for circuit switched connections, packet switched connections and semipermanent connections.

To form an interface, a signalling channel is also needed. A common interface is the 2B+D interface. It consists of two B-channels for speech/data and one D-channel for signalling.

PABX Private Automatic Branch eXchange PDC Public Destination Access Code PDN Public Directory Number PNR Private Network Routing PSTN Public Switched Telephone Network SCN Switched Circuit Network SSPC Static SemiPermanent Connection TCM Travelling Class Mark TCP Transmission Control Protocol TLU Trunk Line Unit TUP Telephone User Part VCU Voice Compression Unit

Note: In order to fully utilize the system's netservice capability, alternative routes that support netservices shall be initiated as the first choice(s) to the primary route. The requested service will fail if an alternative route not supporting netservices is used. Use the routes that not support netservices as last alternative route choices.



BC - Bearer Capability

The bearer capability is set for each outgoing route when initiated. It states the type of calls the line is capable of transmitting, and is depending on the bandwidth of the line, if compression is used etc.

The bearer capability of a route is set to one or more of the following type of calls:

In the same way as for the routes, each extension will have a bearer category set when initiated. When an external call from an extension is made, a request for an external line with matching bearer capability is made. If there is no such line available the call will be rejected.

If the call is transited over an exchange and onto another external line a matching bearer capability (if it is known) is requested again.

The requested bearer capability is part of the protocol for signalling systems based on MOS. On CAS systems no information of requested bearer capability is transferred.

Call metering

The possibility to detect and store call metering (charging) pulses from the public exchange on an outgoing call. As there are many standards for the conveyance of the pulses, different call metering boards (CDUs for 50 Hz, 12 kHz and 16 kHz) are available for analogue trunks, (CDUs are only for sustaining). There is also the possibility to have call metering equipment directly on the trunk line board.

CAS - Channel Associated Signalling

The traditional method of signalling between two exchanges. The signals necessary for the traffic carried by a channel, are transmitted in the channel itself or in a channel permanently associated with it. In other words: Speech and signals travel together.

CCS - Common Channel Signalling

A method of signalling between two exchanges. Signals relating to a number of channels are transmitted over a single data link, in addressed messages. In other words: Speech and signals travel independently, both in time and media.

CCSS7 - Common Channel Signalling System No. 7

- 3.1 kHz Audio. Telephony and/or data calls with modem. - Speech. Telephony calls only. - 7 kHz, high quality speech (e.g. used for sports commentators). - 64 kbit/s Unrestricted digital channel (64K-C). Modemless data calls. Also called 64 kbit/s Clear

channel (hence the C in 64K-C). - 64 kbit/s Restricted digital channel (64K-R). Modemless data calls, US market. - 16 kbit/s Unrestricted digital channel. Compressed voice calls and 16 kbit/s subrate data.

Note: There are two types of call metering boards; detection boards and the optional filter boards. Also, since one call metering board only can handle a given number of external lines, a number of boards may be necessary.



The overall objective of CCSS7 is to provide an internationally standardized general purpose common channel signalling system, optimized for operation in public digital telecommunication networks in conjunction with stored program controlled exchanges.

CCSS7 is a common channel signalling system defined for 64 kbit/s operation between exchanges. The signalling system uses signalling links for transfer of signalling messages between exchanges or other nodes in the telecommunication network served by the system. The system is normally applied with redundancy of signalling links and it includes functions for automatic diversion of signalling traffic to alternative paths in case of link failure. The capacity and reliability for signalling may thus be dimensioned by provision of a multiplicity of signalling links according to the requirements of each application.

Charging

The same as call metering, see above.

CO - Central Office

An exchange in the PSTN. Another name often used is PE (Public Exchange).

CSI - Call Service Information

CSI is used for similar reasons as FRL/TCM.

D-Channel

A 16/64 kbit/s channel used in ISDN for signalling, mainly signalling for circuit switched connections. The D-channel itself uses packet switching. When it is not used for signalling it can be used for packet switched data traffic.

DID - Direct In Dialling

Enables subscribers in the public network to dial a PABX extension directly, i.e. without assistance from the PABX operator.

Another term for this feature is DDI, Direct Dialling In.

DISA - Direct Inward System Access

Enables authorized users to call in to a PABX and get access to the PABX's services, except those services that require a procedure.

DISA calls can be established via direct in dialling external lines or via manual external lines (central office external lines).

D over B signalling - D-Channel signalling within a B-channel

D over B is used with semipermanent connections, to form a tie line with DPNSS functionality between ASB 501s via a public network.

A PCM interface is used, but one of the B-channels is used for signalling. The B-channel that serves as D-channel is called D over B -channel. The channel (time slot 16) that normally would be used for signalling is not used at all for the APNSS route.



DPC - Destination Point Code

The destination point code is the part of the label in a CCSS7 signalling message which uniquely identifies the signalling point to which the message is finally addressed.

DPNSS - Digital Private Network Signalling System

A signalling system designed to extend services available for extensions in a single PABX to extensions in other PABX exchanges in a private network. To the user the whole private network will behave like one PABX regarding services.

DPNSS utilize digital external lines and common channel signalling (CCS).

DRA - Dynamic Route Allocation

A feature for building a private network offering net services, without having to lease tie lines. Instead the PABXes' public interfaces are used to setup temporary connections that are used as tie lines between the PABXes dynamically.

DTMF - Dual Tone Multi Frequency signalling

A tone signalling scheme used for signalling from telephones to exchanges and for register signalling between exchanges. Ten decimal digits and two auxiliary characters (* and #) are represented by a combination of two frequencies. A frequency from the low group [697, 770, 852, 941] (Hz) is combined with a frequency from the high group [1209, 1336, 1447, 1633] (Hz). All in accordance with CCITT Q.23 recommendations.

EFM - External Follow Me

EFM enables an extension to temporarily divert calls towards non-CCS private networks and towards the PSTN or public ISDN.

ECMA QSIG - European Computer Manufacturers Association Q-signalling

Part of ISDN as a system for signalling between exchanges within a private network. It is an adaptation of DSS1 for usage between PABXes.

Usage of ECMA QSIG enables ASB 501 to have ISDN connections to other manufacturers PABXes, and function as gateway between standard ISDN private networks and DPNSS networks.

E&M signalling

The E&M interface consists of four to eight wires (when used in ASB 501 environment), of which two are used only for signalling. These two wires are called E and M, E (Ear) is used for reception and M (Mouth) is used for sending of signals to the co-operating exchange.

Enbloc sending / Overlap sending

Expressions used in ISDN.

Enbloc sending means that the exchange awaits the whole external number to be dialled before sending it in one block.



Overlap sending means that the digits are sent one by one, as soon as they are dialled.

ERWT - Expensive Route Warning Tone

Provides a warning tone to the user when the system has selected an expensive route for the outgoing call.

ETE DTMF - End-To-End signalling DTMF

A signalling method in which DTMF tones are transmitted from one end of a multi-link connection to the other end. The DTMF tones are interpreted as signals at the terminating end.

Sending of DTMF tones while in speech state enables communication with e.g. interactive answering machines.

ETN - Electronic Tandem Network

See RLT

FRL / TCM - Facilities Restriction Level / Travelling Class Mark

Also called Trunk call barring , the FRL/TCM enables selective restriction of outgoing traffic. Every user (e.g. extension or incoming route) is given an FRL value which is passed through the private network from one node to another as the user's TCM. Furthermore every route choice that is defined for a given destination is assigned an FRL value.

To be permitted to use a certain route the A-party's FRL value must be the same as or greater than the FRL value of the route.

FRL/TCM is not used for restriction purposes in the originating exchange, as opposed to Priority routing. Apart from this, the two features are very much alike.

See also the application system parameter PARNUM=106.

Gateway exchange

An exchange used primarily as a switching point for traffic between other exchanges. Specific for the gateway exchange is that in ASB 501 environment it connects routes with different signalling systems.

H.323 signalling system

H.323 is an ITU-T recommendation for all issues related to multimedia communications over packet based networks, like e.g. TCP/IP networks.

Routes initiated following this standard (H.323 routes) allow exchanging signalling and media, if possible, directly through the packet network. In that case, other types of media different than voice (video, data) are also allowed except in the case if either of the originating or terminating board is IPLU and other board is ELU32. It is recommended that all the routes that use video or data should go through IPLU boards alone or ELU32 boards alone.

IDNX - Integrated Digital Network eXchange

Used in networks as a complement to the ASB 501, primarily for cost efficiency on long distance



traffic. The IDNX uses mainly voice compression to increase the capacity on an existing transmission media. By not having to add more cables to increase the capacity, or retain capacity with fewer cables (leased at high costs) a lot of money can be saved. This is compared to the cost of an IDNX system.

IDNXes are set up as gateway exchanges near all the exchanges/sites and the long interconnects are between the IDNXes. The IDNX can handle different signalling systems with varying intelligence.

In an ISDN network the Priority routing information is used by a connected IDNX to determine the service profile to be used for the call.

Individual number translation

Individual number translation is a part of the PNR facility. The translation data are initiated together with the PNR access code in the PNR destination table.

Each PNR access code is assigned two sets of translation data, one suggested for translation to public directory numbers and the other for additional translation if the PABX is connected to a second network (public or private).

IP VPN - Virtual Private Network over IP network

IP Virtual Private Network is a service in a public IP network (like the Internet) that allows proprietary signalling among a number of PABXes that support communications over packet based networks, via a protocol like H.323. The IP VPN enables calls made between the PABXes as if they were made in a private network, with the functionality level of a private PABX network.

ISDN - Integrated Services Digital Network

A fully digital network, providing end-to-end digital transmission from the originator to the final destination, over a limited set of standard user-network interfaces. The network supports both voice and data applications. Public ISDN and private ISDN differ.

LCR - Least Cost Routing

Allows the private exchange to select the most economical route for an outgoing public call. The exchange will check the dialled number to see if the private network can be used (as described below), and then route the call within the private network as close to the destination as possible.

There are three situations the system recognizes:

The dialled destination is an extension in the own exchange. The dialled destination is in the private network and can be reached completely via the private network. The dialled destination can be reached partly via the private network.

The user first have to dial an LCR access code to activate the LCR. The system is then ready to analyse the dialled number.

Loop avoidance

The loop avoidance feature is necessary in A/DPNSS networks where each node is allowed to carry out overflow traffic. It is used to avoid that a call is looped back to a node which has already routed



the call, thus avoiding an infinite loop in the network.

Each call is assigned a loop avoidance counter which is decremented in every node it passes through. When the counter reaches value zero, the call attempt is aborted. The initial value of the counter is set per network. Loop avoidance is used for private network calls.

See also transit counter.

LS - signalling Link Set

A signalling link set consists of a number of signalling links between two adjacent CCSS7 signalling points.

MCT - Malicious Call Tracing

Used for tracing malicious calls, primarily calls from the public network (ISDN, CCSS7) to a PABX. The tracing is activated by a procedure or programmable key. When activated it will cause an alarm and printout/log in the interworking local exchange (in the public network). The printout/log will contain e.g. the calling number, called number, date and time.

For the CCSS7 signalling system the MCT feature is bidirectional, which means that the public network can initiate MCT on a call originated in a PABX.

MFC - Multi Frequency Compelled

A tone signalling system used for register signalling between exchanges.

The tone signals are created by combining two frequencies from a group of 6 frequencies. A tone signal in the forward direction is created using frequencies from the forward group of frequencies [1380, 1500, 1620, 1740, 1860, 1980] (Hz). A backward signal by using frequencies from the backward group [1140, 1020, 900, 780, 660, 540] (Hz).

The different combinations allow 15 different signals to be represented in each direction. Another 15 signals in each direction are possible by letting the same 15 tones represent 15 other signals. This is done by changing signal group (ordered with one of the backward signals). The two forward signal groups are Group I and Group II, the backward signal groups are Group A and Group B.

After sending a forward signal the sending exchange awaits a backward signal, from the receiving exchange to confirm reception of the forward signal, before sending the next forward signal. Hence the name Compelled .

A forward signal from Group I will be acknowledged with a backward signal from group A, until the backward signal ordering changing of groups is sent. After this Group II and Group B are used. The tones are the same as before, but they now represent other signals.

MFPB - Multi Frequency Push Button

The same as DTMF.

MTP - Message Transfer Part

The message transfer part is the part of the CCSS7 node which ensures the reliable transfer of signalling messages between user parts, e.g. TUP. The MTP defines a range of functions by which



different signalling network configurations may be realized. Any application of CCSS7 requires that an appropriate selection of these functions is applied depending on the intended use of the system and the characteristics of the telecommunication network concerned.

OPC - Originating Point Code

The originating point code is that part of the label in a CCSS7 signalling message which uniquely identifies the signalling point in which the message originated.

PABX - Private Automatic Branch eXchange

A PABX is an exchange in a private telephone network, as opposed to an exchange in the public network. ASB 501 is a PABX.

Packet-switched network

Type of network in which relatively small units of data (called packets) are routed based on the destination address contained within each packet. Each packet can follow a different path through thenetwork. Breaking communication down into packets allows the same data path to be shared among many users in the network.

PNR - Private Network Routing

PNR is used for calls terminating within the private network. PNR provides enhanced routing and number translation capabilities for the private network. Several PNR access codes, assigned in the PNR destination table, may use the same RCT to find a way through the private network.

Priority routing

Priority routing enables selective restriction of outgoing traffic. Every user (e.g. extension or incoming route) is assigned a priority routing category called Call Service Information (CSI) which is passed through the private network from one node to another. Furthermore every route choice that is defined for a given destination is assigned an authorization list called Call Service Information Users (CSIU).

To be permitted to use a certain route the A-party's CSI value must be allowed access by the CSIU of the route.

Priority routing is used for restriction purposes in the originating exchange, as opposed to FRL/TCM. Apart from this, the two features are very much alike.

In an ISDN network the priority routing information can be used in one out of two ways. Either for network access restriction as described above, or by a connected IDNX to determine the service profile to be used for a call. If the feature of network access restriction is required in combination with the IDNX feature, the FRL/TCM feature can be used for network access restriction.

RCT - Route Choice Table

An RCT is a table that consists of a primary route choice and its alternatives. Translation information is provided (SRT, TRC, PRE, ADC, etc.) for each choice.

An RCT is accessed either directly with the dialled external destination code or with a fictitious



external destination code provided after an LCR or PNR analysis. There is one RCT for each external destination code.

Rerouting

The expression rerouting is used in the ASB 501 environment for three different traffic cases.

RLT - Release Link Trunk

A feature only for the US market. The Electronic Tandem Network (ETN) can only be initiated if the RLT feature exists in the exchanges. (ETN is a variety of the centralized operator features in a private network using CAS external lines). The RLT feature utilize the internal group hunting group feature. See also the operational directions for INTERNAL GROUP HUNTING .

Route

A route is a number of external lines with the same characteristics. Together they form a route.

Random Line Selection

Random line selection is a method of selecting lines. The random line selection is only supported by CCSS7 routes.

For random line selection the first choice is to select a line from the group of lines that are controlled by the own exchange, out of that group the line that has been released for the longest time is chosen. First the own LIM is searched, then if no free line is found the other LIMs are searched. However, if all lines controlled by the own exchange are busy, a line will be chosen from the group of lines controlled by the cooperating exchange. Out of that group the line that has been released for the shortest time will be chosen.

SCN - Switched Circuit Network

Type of network in which the communication circuit (path) for the call is set up and dedicated to the

1. Rerouting of an incoming call, which meets busy, no answer, congestion etc. to an answer position in that exchange.

2. Rerouting of an incoming call, which meets busy, no answer, congestion etc. to an answer position in another exchange.

3. Rerouting (crank back) takes place upon receipt of a congestion signal from an exchange which has encountered a busy primary route.



participants in that call. For the duration of the connection, all resources in that circuit are unavailable for other users.

SL - Signalling link

A signalling link is a signalling path between two adjacent CCSS7 signalling points. It is provided by level 1 and level 2 of the message transfer part for the reliable transfer of messages between user parts e.g. TUP.

SP - Signalling Point

The Signalling Point is a CCSS7 node which originates, transfers or receives messages. It is identified by a unique binary code, Signalling Point Code.

Signalling route

The pre-defined path, consisting of a succession of signalling points/signalling transfer points and the interconnecting signalling links, that a message takes through the signalling network between the origination point and the destination point is the signalling route for that signalling relation.

Signalling route set

A route set consists of a number of signalling routes with the same origination point and the same destination point. All the signalling routes that may be used between an originating point and a destination point by a message traversing the signalling network is the signalling route set for that signalling relation.

SPC - SemiPermanent Connections

Semipermanent connections are available in some public networks, as an alternative (usually more cost effective) to leased lines, where netservices over the public network is desired.

An SPC is a single B-channel (with no signalling channel). A leased line is a number of B-channels, with a dedicated D-channel. The word semipermanent comes from the fact that the connections are set up by command between two nodes in the public network. The connections remain permanent until removed by command again.

SPCs are used in conjunction with D over B signalling. One SPC is used for conveying the D-channel. The other B-channels are used as the B-channels they are, using the D over B -channel as their dedicated D-channel. This enables netservices over a public network otherwise not supporting them.

SSP - Start Selection Point

Number of digits in a CCSS7 set-up (initial address) message. The digit appointed by the SSP is the last digit included in the message.

SSPC - Static SemiPermanent Connections

Static semipermanent connections are used in an ASB 501 to connect two multiple positions to each other via the switch in a static connection. The effect is the same as if they had been interconnected with a cable.

Transit exchange



An exchange used primarily as a switching point for traffic between other exchanges.

In ASB 501 environment a transit exchange is usually an exchange that interconnects routes with the same signalling system.

Transit counter

The transit counter feature is necessary in ISDN and H.323 networks where each node is allowed to carry out overflow traffic. It is used to avoid that a call is looped back to a node which has already routed the call, thus avoiding an infinite loop in the network.

Each call is assigned a transit counter which is incremented when the overflow is carried out in a node. When the transit counter reaches a preset maximum value the call attempt is aborted. This maximum value is set per network. Transit counter is used for private network calls.

See also loop avoidance.

TUP - Telephone User Part

The telephone user part is the part of a telephone exchange which uses the CCSS7 signalling system to control telephone calls and circuits.

VPN - Virtual Private Network

Virtual Private Network is a service in a public network (primarily ISDN) situated in between a number of PABXes. The VPN enables calls to be made between the PABXes via the VPN as if the call was made in a private network, with the functionality level of a private PABX network.

The VPN's size and capacity are regulated in the agreement between the public network operator and the PABX customer.

3 Basic signalling Exchanges that are connected to each other communicate by means of signalling. This is how the exchanges tell each other that a call is being made, what number is dialled, that either party has hung up, etc.

The communication between different exchanges can be done via either switched circuit networks or packet-switched networks. Traditional signalling systems (e.g., ISDN) work over switched circuit networks and are based on either CAS or CCS ( see 3.1 CAS and CCS ). However, the signalling system defined in the H.323 recommendation works over packet-switched networks.

3.1 CAS and CCS At present there are two signalling principles used in SCN networks. The division in principles is based on how the signals are transmitted in relation to the speech channels they belong to. The division is sort of a division in old and new.

CAS

Channel Associated Signalling



3.2 Line and register signalling CAS is traditionally divided into line signalling and register signalling. There is no need for this division in CCS.

Line signals are simple information in contrast to register signals. Line signals are needed during the whole call while register signals are used only during the call set up.

By dividing the signalling equipment into register and line signalling equipment, and using the more complex register equipment only while the address information is transmitted, one register equipment may be used to serve many lines.

Notice the difference between this division based on what information the signals transfer, and divisions based on the different principles of signalling (e.g. CAS, CCS see above) or techniques used to transfer the signals (e.g. impulsing, tone code).

This is the traditional principle for signalling.

To each speech channel belongs a fixed and unambiguously defined signal path:

either attached to the speech channel, i.e. the signals are transmitted with the speech channel.

This is called inband signalling.

or associated with the speech channel, i.e. the signals are transmitted in their own signal channel separate from the speech channel.

This is called outband signalling.

In other words: Speech and signals travel together.

There is a big variety of different signalling techniques used in CAS, in some cases inband and outband signalling are combined.

CCS Common Channel Signalling

The speech channels use a common data link for transmission of all signals. A signal is transferred as a signal message to which an address is tied. The address states which speech channel the signal belongs to.

In other words: Speech and signals travel independently, both in time and media.

ISDN, DPNSS and CCSS7 are examples of signalling systems using CCS.

Line signalling Seizure, answer and clearing are examples of line signals.

Examples of techniques used for line signalling are DC signalling (Direct Current) and digital signalling (in time slot 16 on a PCM link).

Register signalling This is mainly used for conveying the called number.

Examples of techniques used for register signalling are impulsing (decadic pulsing)



3.3 Example of signalling In the figure below is an example of signalling between exchanges using a CAS signalling system. The example shows a basic call from A to B where the B-party hangs up first.

4 Prerequisites Network Services are administered with the LC commands.

and tone code (e.g. DTMF, MFC).

Figure 3-1. Signalling for a basic call



5 Aids I/O terminal.

6 References In these operational directions references are made to the following documents:

7 Execution 7.1 Routing, general To set up a route in the ASB 501 system, a selection of MML commands are necessary.

A route is identified by the system by its route number which is a fictitious sequence number. The route is given certain characteristics, some characteristics are used by the system (command ROCAI ) and others are used by the interface between the system and the external line (command RODAI ).

An external line is physically connected to the system by connecting it to the front of a TLU board. The back of the TLU board is connected to the switch at a number of equipment positions. The number of equipment positions depends on the type of TLU board.

An external line is logically connected to the system by associating a route to an equipment position (command ROEQI ). At the same time the external line (equipment position) is given a sequence number based on what LIM the line is connected to. This sequence number is used for outgoing calls

Operational directions: Account code Analogue extension Application system parameters Authorization code for extension IP networking Least cost routing Message transfer part data Number analysis PABX operator traffic Route data Special purpose extension

Command descriptions: Account code, AO Analogue extension, EX Application system parameters, AS Authorization code for extension, AU Least cost routing, LC Message transfer part data, MT Number analysis, NA PABX operator traffic, OP Route data, RO Special purpose extension, SP



at the line selection which can be done in different ways. A route can have external lines in several LIMs, then providing distribution of the traffic load for a route.

H.323 routes represent an exception to the previous statements. First, this type of routes make use of an IP interface board (ELU32/IPLU) instead of a TLU board, since it is the same interface as the IP extension. ELU32/IPLU boards are connected directly to the data network at the front side. There is no association between physical equipment positions in the board and external lines. ELU32/IPLU boards are capable of supporting more calls than equipment individuals, given that not all calls need board media resources and if needed, those resources can be borrowed from another board. So, it is possible to initiate more external lines than board positions. External lines are not attached to an equipment position. Every H.323 route is associated to a group of ELU32/IPLU boards and is only allowed to use resources (signalling and media channels) within that group. It is not necessary to use the same ELU32/IPLU boards for signalling and media of the same call, but must belong to the same group of boards.

7.2 Routing, CCSS7

To set up a CCSS7 signalling link in the ASB 501 system, a selection of MML commands are necessary.

MTSSI

The first thing to do is to initiate a link set with the command MTSSI .

Figure 7-1. Signalling description for CCSS7 Note LIM 1 and LIM 2 belong to the same PABX but are located at different places. Therefore

they may have access to two different exchanges in the public network.

In the figure above the route set RS1 is set up between Signalling Point Code (SPC) (A) and SPC(X). Signalling routes SR11 and SR22 belongs to RS1. A route set RS2 has to exist between SPC(A) and SPC(Y) but that is not shown in the figure.



Parameters of special importance are OPC, DPC and LNKSET.

The parameters OPC and DPC are determined by the SPC values. The SPC values are provided when requesting a CCSS7 access from the public network.

Parameter LNKSET states a specific signalling link set.

MTSLI

Secondly, define the characteristics for the signalling links using command MTSLI . Parameters of special importance are LINK, LNKSET, PCMID and SLC.

Parameter LNKSET states a specific signalling link set.

Parameter PCMID states the PCM link identity of the board where the signalling link is situated. The value is used to form the complete circuit identification code (CIC) of all external lines assigned to the board. The parameter value specifies the most significant seven bits of the CIC. The remaining five bits are determined by the corresponding time slot used for the speech connection of the external lines.

Parameter SLC states the code of a signalling link connecting two points in a common channel signalling system No.7 network. The SLC is sent in message signal units (MSUs) to indicate the signalling link, connecting the destination and originating points, to which the message is related.

MTSTI

Thirdly, the signalling route set shall be initiated with command MTSTI . Parameters of special importance are ROUSET, DPC and TEST.

Parameter ROUSET states a signalling route set number.

Parameter TEST states whether a signalling route test will be performed or not.

MTSRI

Next to do is to initiate the signalling routes using command MTSRI . Parameters of special importance are SIGROU, ROUSET, LNKSET and PRIO.

Parameter SIGROU states a signalling route number.

Parameter PRIO states what priority the signal route has.

MTSDC

Finally the signalling links shall be activated. This can be done link by link or the whole link set by using command MTSDC . Parameters of special importance are LINK, LNKSET and DEACT.

Parameter DEACT states whether the signalling link shall be deactivated (YES) or activated (NO). If the parameter is omitted the value NO is assumed.

Trunk lines



After initiating the link set and signalling links and the route sets and signalling routes the trunk lines shall be initiated following the description in the next section. Variables that are of special importance for CCSS7 are:

SERV D3 : Type of route, shall be set to 0, trunk line.

SERV D4 : Call metering characteristics, shall be set to 1, call metering route.

ADC D20-D21 : Start Signalling Point (SSP).

SIG D12 - Netservices, has to be set to 0, no net service facilities.

CNTRL : Decides whether the trunk is controlled by its own (YES) or cooperating (NO) exchange. If OPC is lower than DPC and the trunk individual is odd, the CNTRL parameter shall be set to YES.

7.3 Basic routing Below there is a description of the different commands that are necessary to initiate a route, in order to provide it with its specific categories and characteristics.

ROCAI

The first thing to do is to initiate a route with the command ROCAI . Parameters of special importance are SEL, SERV and SIG.

For parameter SEL the following characteristics are of special interest:

Criteria for rerouting at DID traffic.

If any rerouting criteria are set, command RODNI must be used to define the answering position to which the call shall be rerouted to.

For manual incoming routes, the answering position is primarily defined by the commands OPCTS and OPCGS , see operational directions for PABX OPERATOR TRAFFIC .

Selection of a line at outgoing traffic.

For instance, the line selection can be done in the way that the calls are evenly distributed among the external lines.

For parameter SERV the following characteristics are of special interest:

Whether the system is to handle the route as public (trunk line) or private (tie line).

Used to provide correct ringing signal and display message at the called party.

For parameter SIG the following characteristics are of special interest:

Note For specific characteristics at route initiation and allowed categories for H.323 routes, see operational directions for IP NETWORKING and also see extra facility description for IP NETWORKING .



Whether dial tone after seizure of the external line is to be generated in own or received from the co-operating exchange at outgoing call.

Whether the route has any clear signal.

Used to check if the parties, i.e. a party in own exchange or an incoming or outgoing route, are allowed to be connected. If both parties lack clear signal, the connection of the call is prohibited unless the call is extended and supervised by a PABX operator. PABX operator supervision of extended calls is also stated in parameter SIG.

When the switch shall be through-connected

Type of signalling system, i.e. DPNSS, ISDN, H.323, MFC, decadic pulsing/DTMF or CCSS7

Whether netservices are supported or not for H.323/DPNSS/ISDN routes

For a detailed description of parameter SIG, see section The SIG parameter.

RODAI

Secondly, define the characteristics used by the interface between the external line and the system with the command RODAI . These characteristics are dependent on the type of signalling system and can be found in the parameter description for the external line in question.

There are three parameters for the purpose of stating characteristics. Parameter VARC is used for stating common characteristics, parameter VARI is used for stating characteristics specific for incoming traffic, and parameter VARO is used for stating characteristics specific for outgoing traffic.

Typical characteristics are:

type of register signalling type of MFC whether end of selection (EOS) shall be sent whether B-answer shall be sent whether B-answer shall be received characteristics for different time supervisions specific differences within the concerned signalling system (protocol)

ROEQI

Thirdly, the external line(s) shall be logically connected to the route with the command ROEQI .

NANSI , RODDI

Lastly, if the route allows outgoing traffic, one or more route access codes for external traffic has to be defined.

The route access code shall be initiated as an External Destination number type (ED or EC) with

Note: A value stating a specific characteristic for one type of route does not necessary have the same meaning for another route.



command NANSI , see operational directions for NUMBER ANALYSIS .

The External Destination number is affiliated to an outgoing route by command RODDI .

Parameters of special importance are:

CHO

states whether the route is the primary or an alternative route for the stated External Destination. If an alternative route is defined for an External Destination, this route is selected when no free external line exists in the primary route.

TRC and PRE

If an alternative route is selected, the called number might be modified to enable a connection to the same destination using another connection path.

TRC states the number of digits to truncate starting from the first called digit.

PRE states the new digits which shall be inserted as the first digits. The (first part of) PRE must be initiated as external destination.

If both TRC and PRE are given, the digits stated in PRE are inserted after the number of digits stated in TRC has been truncated.

SRT

states the start position in the called number (possibly modified using TRC and PRE) from which digits shall be sent to the co-operating exchange.

For instance, if number 00 is defined as the route access code for a route and these digits are not to be sent to the co-operating exchange, SRT is set to 3.

7.3.1 The SIG parameter

How to set the SIG parameter depends on the configuration of the private network, and on the signalling systems used.

7.3.1.1 Normal SIG settings

When a PABX is to be connected to the PSTN using a CAS external line (analogue or digital) the SIG parameter is usually set as in the figure below.



7.3.1.2 D 7 - Ringing tone

Example

The figure below is an example of a private network where exchange C cannot send ringing tone. Therefore D 7 =1 is set in exchange B for the route to exchange C.

Imagine a call to the extension in exchange C, made either from the extension in exchange A, or from the extension in exchange B. When exchange B receives B-answer signal from exchange C, the tone sender (TS) in B is disconnected and switch through connections is carried out in exchange B.

EL - Extension Line Interface TL - Trunk Line Interface

Figure 7-2. Normal settings for the SIG parameter

D 7 =0

In most cases the ringing tone is sent across the network as an across the network supervisory tone and D 7 is to be set to 0.

D 7 =1

On some markets though, the called exchange (most often a manual exchange) cannot send ringing tone but only B-answer signal. If this is the case D 7 is set to 1.

The ASB 501 will then, after end-of-selection (EOS), connect a tone sender (TS) and send ringing tone to the A-party (extension, incoming route etc.).



7.3.1.3 D 8 , D 9 and D 10

To be able to set D 8 , D 9 and D 10 correctly, knowledge about the network and network configuration (i.e. the characteristics of the terminal and transit exchanges involved), and how the signalling systems in the different networks work, is necessary.

If the network uses either CCS signalling systems or H.323 signalling, D 8 , D 9 and D 10 are set to 0 for all routes.

D 8 not 0, MFC signalling

The figure 7-5 below is an example of a private network with terminal and transit exchanges using MFC signalling. The transit exchange is of either the trunk transit or the integrated transit type.

Trunk transit - no extensions or PABX operators in own exchange. Integrated transit - extensions and/or PABX operators in own exchange.

MFC is used for register signalling. Analogue or digital external lines are used.

Switch-through-connection takes place in the set up phase in the C exchange. A call from the extension in exchange A, via the exchanges B and C, will overflow and be rerouted in exchange B if the route from C to D is busy.

In the example a call is made from the extension in exchange A to the extension in exchange E. The number dialled is: XY-xyz.

Figure 7-3. Example where SIG D 7 =1

Note: The relationship between SIG D 9 and ADC D 8 . Position D 8 in parameter ADC is set in the command RODDI . It is used by the incoming MFC route so the correct backward MFC signal can be sent. D 8 states at what digit (first, next, previous etc.) the digit sending shall continue.



Figure 7-4. An explanation to the figure 7-5 below



D 9 = 1 and D 10 = 1, SJ type signalling (Swedish railways)

D 9 =1 and D 10 =1 is only used in networks with signalling systems of the SJ type (Swedish railways). See the figure below which is an example of private network with terminal and transit

Figure 7-5. Example of a private network where SIG D 8 =2 is used in A, B and D



exchange using this type of signalling.

MFC is not used for the register signalling.

Direct switch-through-connection in the B-exchange takes place only on traffic from group exchange A.

The characteristics for alternative routing are set to make the originating exchange (exchange A) route a call according to the alternative route(s) associated to the primary route. The primary and alternative routes shall cover all route choices through the transit exchange part of the network.

On the other hand, a call from terminal exchange T will be routed by exchange B according to exchange B's configuration of primary and alternative routes.

D 9 - Rerouting characteristics for transit exchange

Depending on the network configuration and the signalling systems used, rerouting (crank back) in the network shall be done in different ways.

Figure 7-6. Example of a private network using SJ type signalling



The extension in exchange A makes a call that normally would be routed A to B to C to... B is a transit exchange where there is a choice of different routes.

D 9 = 0 - MFC signalling with crank back

If the outgoing route in exchange B is busy the call is overflowed in exchange B. Crank back takes place if the outgoing route in exchange C is busy. A congestion signal is then sent back to exchange B where rerouting is carried out towards exchange D. The established connection A to B remains in both cases.

D 9 = 1 - SJ type signalling (Swedish railways)

Exchange A is the exchange with the route choice table. If an outgoing route in exchange B or C is busy, the connection A to B is cleared after reception of a congestion signal, and the next choice in the route choice table is used for rerouting (i.e. a new call A to B) in A.

7.4 Extended services for outgoing traffic NANLS

For an external number the following can be stated with command NANLS :

After how many digits B-answer can be expected.

This causes reduction of the seizing time on tone receiver/sender, which is a common resource used at digit sending and tone detection.

NAPTS

When dialling an external number where one or more PTS signals are expected, the positions of expected PTS signals in the external number can be set with the command NAPTS . At these positions the system shall connect a tone receiver and await the detection of the PTS signal before the digit sending does continue. This is not relevant for CCSS7 nor H.323 trunks.

NACDS

To prevent specific extensions in the system from calling specific external numbers, there is the possibility with the command NACDS to define different trunk call discrimination (TCD) categories for different external numbers. A route is always associated to a TCD category with the parameter TRAF in command ROCAI .



7.5 A-number request from PSTN

7.5.1 General

In connection to incoming calls from PSTN and depending on the signalling system, there is a possibility to request the A-number which then can be shown on the answering position's display. The signalling systems that support this are certain MFC protocols (e.g. Swiss MFC) and public ISDN in USA (AT). For further information see the documentation for concerned application system. The A-number request is also dependent on the B-party's category stating if A-number request is allowed or not.

7.5.2 Prerequisites

The trunk block used can be TL60/SL63, TL72 or TL30. The incoming route is connected to the PSTN. For TL72 and TL30 register signalling MFC must be used.

7.5.3 Execution

Incoming route support for A-number request is set in parameter SERV, command ROCAI . The category for the B-party is set in parameter ADC and/or SERV for the command groups EX, KS, GH and AC. If the B-party is a PABX operator, PARNUM=153 in command ASPAC states if A-number request is allowed or not.

7.6 A-subscriber charging

7.6.1 General

In connection to incoming calls from PSTN and depending on the signalling system, there is the possibility to decide if the A-subscriber shall be charged or not. An example is a PTT exchange (PTT PABX) with answer positions for e.g. complaints, information etc., so called free of charge answering positions. The signalling systems that support this are certain MFC protocol like Swiss MFC. For further information see the documentation for concerned application system. If the A-subscriber shall be charged or not, is dependent on the B-party's category.

When calling a free party, either MFC backward signal B:6 (which means charging of A-subscriber), or B:7 (which means no charging of A-subscriber) is sent. At answer, and when answer signal is sent and received in the public exchange, charging or not of the A-subscriber is dependent on which of the signals B:6 or B:7 that was previously received.

7.6.2 Prerequisites

The trunk block used can be TL72. The incoming route is connected to the PSTN, and register signalling MFC is used.



7.6.3 Execution

The category for the B-party is set in parameter SERV for the command groups EX, KS, GH and AC. If the B-party is a PABX operator or data extension, PARNUM=153 in command ASPAC states if the A-subscriber shall be charged or not.

7.7 DISA - Direct Inward System Access

7.7.1 General

DISA permits external users to call in to a PABX and get access to some of the PABX's features.

The DISA feature can be accessed via different types of trunks.

Direct in dialling trunks Private tie lines Manual trunks

The dialling procedure for a DISA call is:

DISA number DT * FC * AUTH.CODE # DT Wanted number DISA number DT * FC * AUTH.CODE * FC * ACO.CODE # DT Wanted number

The DISA user has the possibility to charge a call to an account code (tied to e.g. a particular project, department or client), instead of charging the called DISA extension (which is default).

A DISA call requires a DTMF telephone instrument with a key pad providing pound (#) and star (*) keys.

After having completed a DISA call the user must hang up, before a new DISA call can be made.

Some ASB 501 features are not available when making a DISA call:

Features that are accessed by dialling a procedure, except for the account code procedure. Any feature activated by suffix dialling.

7.7.2 Execution

The execution is described using two examples.

The first example is when DID external lines/tie lines are used for DISA.

The second example is when manual external lines are used for DISA.

DT = Dial tone FC = Feature code AUTH.CODE = Authorization code ACO.CODE = Account code



7.7.2.1 Example with DID external lines/tie lines.

Prerequisites

DID external lines/tie lines have been initiated in the ASB 501 with the commands:

ROCAI RODAI ROEQI

Command handling

Initiate a number with number type DI (DISA)

NANSI :NUMSE=11600,NUMTYP=DI;

Define a category for the DISA extension

EXCCS :CAT=50,TRAF=00151515,SERV=00001000,CDIV=001000000;

Initiate an authorization code:

CILCOD is used for the call information logging, i.e. the calls using this authorization code will be logged on the CILCOD stated.

AUCOI :AUTH=1234,CILCOD=11600,CAT=50; (In this example the CILCOD used is the same as the DISA number)

Initiate an account code (optional):

AOCOI :ACO=516; Used for charging an account code instead of charging the DISA extension.

7.7.2.2 Example with manual external lines.

Prerequisites

Manual external lines have been initiated in the ASB 501 with the commands:

ROCAI RODAI ROEQI

Command handling

Initiate a number with number type DI (DISA)

NANSI :NUMSE=11600,NUMTYP=DI;

Define a category for the DISA extension



EXCCS :CAT=50,TRAF=00151515,SERV=00001000,CDIV=001000000;

Initiate day and night service position (= DISA number) for the incoming route

RODNI :ROU=10,DAY=11600,NIG=11600;

Initiate an authorization code:

CILCOD is used for the call information logging, i.e. the calls using this authorization code will be logged on the CILCOD stated.

AUCOI :AUTH=1234,CILCOD=11600,CAT=50; (In this example the CILCOD used is the same as the DISA number)

Initiate an account code (optional):

AOCOI :ACO=516; Used for charging an account code instead of charging the DISA extension.

7.8 DRA - Dynamic Route Allocation

7.8.1 General

The major function is to realize tie lines by establishing dynamic routes between PABXes, over an InterVening Network (IVN) that offers 64 kbit/s B-channels. The idea is to be able to build an intelligent private network without having to lease tie lines. The Dynamic Route Allocation feature makes it possible to interconnect PABXes in an intelligent private network without the usage of permanent or semipermanent connections through the public network.

A dynamic route consists of a number of 64 kbit/s B-channels, Uq-channels. The Uq-channels are compressed to 16 kbit/s channels so that 4 B-channels are carried in one 64 kbit/s bearer channel through the public network. For 16 kbit/s restricted data connections, the 16 kbit/s data channel is connected without being compressed. One channel within the bearer channel is used for signalling between the peer ends, the Dq-channel.

Dynamic routes are established by using temporary Inter PABX connections at the C-reference points (IPCs), that are set up between the PABXes on a per call basis. Unique DID numbers are used to set up the Inter PABX connections. The IPCs utilize the standard interfaces used for connection of the PABXes to the public network.

When a dynamic route is set up through an IVN, using DRA to interconnect the PABXes, the intelligent signalling between the PABXes is achieved by using a signalling channel (Dq-channel) of an intelligent signalling protocol (ISDN ISO QSIG) hidden inside an ordinary bearer channel (B-channel), so called D over B signalling.

The set up of the dynamic route is traffic controlled from the originating PABX.



7.8.2 Prerequisites

A public digital route with Direct In Dialling (DID) must be initiated in each of the PABXes that are to be interconnected using dynamic routes. In order to use statically connected D-channel a private tie line must be initiated in the system.

7.8.3 Execution

7.8.3.1 Example with a statically connected D-channel

First set up the VCU boards using configuration 4. CONFIG=4 means four 64 kbit/s inputs and one 64 kbit/s output (comprising four 16 kbit/s compressed/switched subchannels).

VCCOI :BPOS=1-1-30,CONFIG=4; VCCOI :BPOS=1-1-32,CONFIG=4; .

Then set up the DRA resources using resource type 1. RESTYP=1 means that a 4B channel group is used.

DAREI :EQU=1-1-30-0,RESTYP=1; DAREI :EQU=1-1-32-0,RESTYP=1;

Set up a route for outputs and D-channel using static connections, SEL D 4 =2 means special route for VCU outputs and D-channel . The route shall be barred for outgoing traffic (SEL D 3 =0) and shall not be allowed to use any net services (SIG D 12 =0). To enable static connection the type of

Figure 7-7. A private network using dynamic routes

The figure visualizes the basic terminology of DRA



feature must be specified to Voice Compression (VARC D 4 =1).

ROCAI :ROU=95,SEL=710200000000001,SIG=311110000030,TRAF=03151515,TRM=4, SERV=3110000000,BCAP=100000; RODAI :ROU=95,TYPE=TL96,VARC=00010000,VARI=00000000;

Set up the VCU boards using configuration 3. CONFIG=3 means three B-channels where each B-channel can be used for compressed speech or switched data and one inband 16 kbit/s D-channel.

VCCOI :BPOS=1-1-20,CONFIG=3; These three B-channels are free to use for ordinary VCU calls.

Initiate the 0- individual on the VCU board first. The 0-individual is used as the signalling terminal output from the VCU board.

ROEQI :ROU=95,TRU=1-1,EQU=1-1-20-0;

Initiate the VCU D-channel after that. It is located at individual 15 on the VCU board.

ROEQI :ROU=95,TRU=1-2,EQU=1-1-20-15;

Then link the output, using Static SemiPermanent Connections (SSPC), to the outgoing private digital tie line (EQUB). The outgoing private digital tie line must be initiated in each of the PABXes first.

SEMII :EQUA=1-1-20-0,EQUB=1-1-00-1;

Initiate a special route for VCU outputs and D-channel (SEL D 4 =2), only allowing for 64 kbit/s unrestricted traffic. The route shall be open for outgoing traffic (SEL D 3 =1) without net services (SIG D 12 =0). To enable Dynamic Route Allocation the type of feature must be specified to Dynamic Route Allocation (VARC D 4 =2).

ROCAI :ROU=96,SEL=711200000000001,SIG=311110000030,TRAF=03151515,TRM=4, SERV=3110000000,BCAP=100000; RODAI :ROU=96,TYPE=TL96,VARC=00020000,VARI=00000000,VARO=00000000;

Initiate external dynamic lines for the special route for dynamic outputs and D-channel.

ROEQI :ROU=96,TRU=1-1; ROEQI :ROU=96,TRU=1-2;

Initiate IPLs (Inter PABX Link) using statically connected D-channels (DCAT=0), in own exchange and including peer PABX information (special destination). This side will act as master of a connection. Set the B-channel to enter speech state when ringing starts (BCAT=1). OWNNO is the DID part of the calling party number, PEERNO is the DID part of the number to use when calling the peer side and PRE is used as pre-digits to insert in front of the DID number to form a complete external number.

NANSI :NUMTYP=ED,NUMSE=99999; RODDI :DEST=99999,ROU=96;



DAILI :IPL=1,LIM=1,SIDE=MASTER,DCAT=0,BCAT=1,OWNNO=99999,PEERNO=88888, PRE=0455;

Set up the dynamic tie line route (SEL D 4 =3 means route with dynamically allocated external lines) with net service facilities (SIG D 12 =1). This route shall support the bearer capabilities 3.1 kHz Audio, Speech and 16 kbit/s unrestricted. The hardware shall be dynamically connected (VARC D 8 ) and all speech calls shall be compressed with LD-CELP (VARC D 4 =3). The D-channel shall use the signalling protocol for Voice Compression (VARO D 4 =4).

ROCAI :ROU=3,SEL=711300000000001,SIG=311100000031,TRAF=03151515,TRM=4, SERV=3110000000,BCAP=001101; RODAI :ROU=3,TYPE=SL60,VARC=0003031C,VARI=15480000,VARO=06C40000;

Initiate external dynamic lines for the dynamic tie line route. The D-channel position is given in SQU-parameter without LIM number. INDDAT specifies which interface the external dynamic line belongs to and also the channel number within the interface.

ROEQI :ROU=3,TRU=1-1,SQU=1-20-15,INDDAT=000000000101; ROEQI :ROU=3,TRU=1-2,SQU=1-20-15,INDDAT=000000000102; ROEQI :ROU=3,TRU=1-3,SQU=1-20-15,INDDAT=000000000103; ROEQI :ROU=3,TRU=1-4,SQU=1-20-15,INDDAT=000000000104; ROEQI :ROU=3,TRU=1-5,SQU=1-20-15,INDDAT=000000000105; ROEQI :ROU=3,TRU=1-6,SQU=1-20-15,INDDAT=000000000106; ROEQI :ROU=3,TRU=1-7,SQU=1-20-15,INDDAT=000000000107; ROEQI :ROU=3,TRU=1-8,SQU=1-20-15,INDDAT=000000000108; NANSI :NUMTYP=ED,NUMSE=864; RODDI :DEST=864,ROU=3,SRT=1,ADC=06061000000002500060000000; RONDI :ROU=3,EXNOPR=6-850,EXNOPU=0-08;

7.8.3.2 Example with dynamically connected D-channel

First set up the VCU boards using configuration 3 and 4. CONFIG=3 means three B-channels where each B-channel can be used for compressed speech or switched data and one inband 16 kbit/s D-channel and CONFIG=4 means four 64 kbit/s inputs and one 64 kbit/s output.

VCCOI :BPOS=1-1-30,CONFIG=3; VCCOI :BPOS=1-1-32,CONFIG=4;

Then set up the DRA resources using resource type 2 (RESTYP=2 means that a 3B+D channel group is used) and resource type 1 (RESTYP=1 means that a 4B channel group is used).

DAREI :EQU=1-1-30-0,RESTYP=2; DAREI :EQU=1-1-32-0,RESTYP=1;

Set up a special route for dynamic outputs and D-channel (SEL D 4 =2) only allowing for 64 kbit/s unrestricted traffic. The route shall be open for outgoing traffic (SEL D 3 =1) and shall not be allowed to use any net services (SIG D 12 =0). To enable Dynamic Route Allocation the type of feature must be specified to Dynamic Route Allocation (VARC D 4 =2).



ROCAI :ROU=96,SEL=711200000000001,SIG=311110000030,TRAF=03151515,TRM=4, SERV=3110000000,BCAP=100000; RODAI :ROU=96,TYPE=TL96,VARC=00020000,VARI=00000000,VARO=00000000;

Initiate external dynamic lines for the special route for dynamic outputs and D-channel.

ROEQI :ROU=96,TRU=1-1; ROEQI :ROU=96,TRU=1-2;

Initiate IPLs (Inter PABX Link) using dynamically connected D-channel (DCAT=3), in own exchange and including peer PABX information (special destination). This side will act as master of a connection. Set the B-channel to enter speech state when ringing starts (BCAT=1). OWNNO is the DID part of the calling party number, PEERNO is the DID part of the number to use when calling the peer side and PRE is used as pre-digits to insert in front of the DID number to form a complete external number. The DELAY parameter states how long time an IPL has to be idle before the D-channel is disconnected, in this case 10 minutes.

NANSI :NUMTYP=ED,NUMSE=99999; RODDI :DEST=99999,ROU=96; DAILI :IPL=1,LIM=1,SIDE=MASTER,DCAT=3,BCAT=1,DELAY=00-10,OWNNO=99999, PEERNO=88888,PRE=0455;

Set up the dynamic tie line route (SEL D 4 =3 means route with dynamically allocated external lines) with net service facilities (SIG D 12 =1). This route shall support the bearer capabilities 3.1 kHz Audio, Speech and 16 kbit/s unrestricted. The hardware shall be dynamically connected (VARC D 8 ) and all speech calls shall be compressed with LD-CELP (VARC D 4 =3). The D-channel shall use the signalling protocol for Voice Compression (VARO D 4 =4).

ROCAI :ROU=3,SEL=711300000000001,SIG=311100000031,TRAF=03151515,TRM=4, SERV=3110000000,BCAP=001101; RODAI :ROU=3,TYPE=SL60,VARC=0003031C,VARI=15480000,VARO=06C40000;

Initiate external dynamic lines for the dynamic tie line route. INDDAT specifies which interface the external dynamic line belongs to and also the channel number within the interface.

ROEQI :ROU=3,TRU=1-1,INDDAT=000000000101; ROEQI :ROU=3,TRU=1-2,INDDAT=000000000102; ROEQI :ROU=3,TRU=1-3,INDDAT=000000000103; ROEQI :ROU=3,TRU=1-4,INDDAT=000000000104; ROEQI :ROU=3,TRU=1-5,INDDAT=000000000105; ROEQI :ROU=3,TRU=1-6,INDDAT=000000000106; ROEQI :ROU=3,TRU=1-7,INDDAT=000000000107; NANSI :NUMTYP=ED,NUMSE=864; RODDI :DEST=864,ROU=3,SRT=1,ADC=06061000000002500060000000; RONDI :ROU=3,EXNOPR=6-850,EXNOPU=0-08;

7.9 ERWT - Expensive Route Warning Tone



7.9.1 General

The ERWT feature provides a warning tone to the user when the system has selected an expensive route for the outgoing call.

When the user has dialled a complete external number and the system has chosen a route that is marked expensive, the user receives a warning tone. The expensive route is seized and all digits except the last one are sent to co-operating exchange.

At reception of the warning tone the user can either terminate the call or wait for the time out of the warning tone. On time out, the system will continue to process the call by sending out the last digit.

Digits which are dialled during the tone sending (ERWT) are ignored by the system.

7.9.2 Prerequisites

-

7.9.3 Execution

Whether the system shall send ERWT or not is set in D 11 in the ADC parameter. The ADC parameter belongs to the RODDI command.

7.10 IDNX Interworking

7.10.1 General

The implementation of ASB 501-IDNX interworking depends on if non-ISDN or ISDN routes (external lines) are going to be used between the ASB 501 and the IDNX.

7.10.1.1 Non-ISDN

If non-ISDN routes are to be used, the normal routing features are used for the ASB 501-IDNX interworking. The transmission media between the ASB 501 and the IDNX are divided into routes which are given different characteristics, such as bearer capability and category. Since no call information is conveyed over the route, the call information must be tied to the route carrying the call.

The IDNX is initiated in a similar manner, giving each route the same characteristics as in the ASB 501.



7.10.1.2 ISDN

If ISDN routes are to be used, the ASB 501 priority routing feature is used for the ASB 501-IDNX interworking.

When the IDNX service selection feature is used the IDNX service selection parameter, IDNX, is used instead of the priority routing parameter, CSI.

The call information is conveyed over the route to the IDNX.

Call routing in the IDNX network is taken care of by the IDNXes. Overflow to the PSTN if the route to the IDNX is busy, is initiated in the ASB 501.

7.10.2 Prerequisites

If ISDN is to be used the ASB 501 priority routing feature cannot be used.

Figure 7-8. ASB 501-IDNX interworking with non ISDN routes

Note: Either the ASB 501 priority routing feature is used for priority routing or for IDNX service selection. Both methods of application cannot exist in the same ASB 501 exchange.

Figure 7-9. ASB 501-IDNX interworking with ISDN routes

Figure 7-10. Network with IDNX backbone



7.10.3 Execution

7.10.3.1 Non-ISDN

The routes are set up as in basic routing with the commands ROCAI , RODAI , ROEQI , ( NANSI ) and RODDI .

Different bearer capabilities are set for the routes to indicate the type of calls the route carries. The IDNX needs this information when it is to decide if compression is to take place.

7.10.3.2 ISDN

With ISDN the following commands are used to initiate the IDNX service selection feature:

For further description of IDNX service selection templates, consult the manuals from the IDNX vendors.

7.11 LCR - Least Cost Routing

7.11.1 General

LCR is a function that enables the system to automatically select the most economical route for an outgoing public call .

The system will detect if the call is made directly to a public network:

is to an extension in own exchange.

may be reached completely via the private network.

(Off-net to On-net routing)

may be reached partly via the private network.

(Best-end Hop-off, Tail-end Hop-off)

LCR will select the cheapest route for the call depending on:

the dialled number

the time of day (optional).

ROCAI (or ROCAC ) The CSI is set to 0, i.e. D 12 =0 in the SEL parameter.

RODII The CSIU parameter must not be set. EXTEI (or EXCCS or EXCAC ) The CSI part of the ROC parameter, D 4 , is used to set the

IDNX service selection template of 0-7, to be used for a call. KSEXI (or KSANI or KSCAC ) The CSI part of the ROC parameter, D 4 , is used to set the

IDNX service selection template of 0-7, to be used for a call.



The function is realized by modifying the dialled public number, based on the information in a number of LCR tables.

A short explanation of how external analysis, RCTs, and destination data records are related:

A call made to the public network, will after a first number analysis (where the call is found to be to an external destination) be passed on to external analysis. The external analysis utilizes a table of destination data records (initiated with command RODDI ), where data about number modification and routing is found.

For each destination (possibly fictitious) an RCT with up to eight linked route choices shall be initiated. Each route choice uses one of the destination data records in the external analysis.

LCR adds features, and increases the capacity of the external analysis (basic routing). LCR enables that one and the same set of destination data records can be used for different called numbers.

The LAC

Least cost routing is invoked when a LAC (Least cost routing Access Code) is dialled.

With basic routing only (no LCR), the dialled number is sent for external analysis when the access code for public calls is detected. With LCR, when the LAC is detected, the system modifies the dialled number to begin with a fictitious destination code, before it is sent for external (or internal) analysis.

By specifying the LAC as the standard access code for calls to the public network (e.g. 9 or 00) the user will not need to remember a special access code to use for LCR calls.

By using basic routing (command RODDI ) an LCR-like function could be implemented without using LCR, but it would require initiation of a lot of destination data records, i.e. quickly use up the limited capacity in the external analysis. Furthermore, it would require the users to use different access codes for LCR calls and non LCR calls.

LCR number data base tables

LCR consists of five number data base tables where the dialled number is modified, before it is sent to external or internal analysis. Any number initiated in any of the LCR tables (apart from the FDT, described later) shall begin with a LAC that is initiated in the number analysis.

The first table is the External Number Table ( LCDDI :TAB=ENT).

This table offers basic analysis of conflict numbers, translation of special numbers, and translation to internal numbers and numbers within own private network (off-net to on-net conversion).

The second table is the Number Length Table ( LCDDI :TAB=NLT). This table shall be used when an exchange has a remote LIM in a different area (other area code).

This table can be used also in branch office scenarios where an exchange in the main site has IP telephones in the branch offices located in different areas (other area codes).

For the US market the NLT can also be used to distinguish between conflicting numbers using a combination of timer and number length analysis.



The third table is the Exceptions Table ( LCDDI :TAB=DNT1).

This, and the DNT2 together with the FDT (see below), are where the main LCR function is realized. Most of the numbers/number series that are to be least cost routed are initiated in these tables.

The DNT1 offers analysis of numbers up to 16 digits long which is good for analysing exception numbers. Exception numbers are numbers that belong to a number series analysed elsewhere (in external analysis with or without LCR), but need to be treated individually.

The fourth table is the Number Table ( LCDDI :TAB=DNT2).

This table only analyse numbers up to 8 digits long and is used for number series.

The fifth table is the Fictitious Destination Table ( LCDDI :TAB=FDT).

This table is the link between the DNT tables and the destination data records of the external analysis.

Finally there is the optional feature to initiate Least cost time zone data in the DNT table (command LCTDI ). This feature is called Time of day . Basically, it offers the possibility to have a call routed differently depending on the time of day and the day of the week.

The first two tables (ENT & NLT) modify the dialled number before it is sent to internal or external analysis.

The two DNT tables modify the dialled number before sending it to the FDT (possibly via time of day if desired). The DNT further prefixes the previously modified number before sending it on to external analysis.

Whether or not data shall be initiated in each table will be described below in the section Execution.

Toll restriction and Forced Account Code may be applied for any call through LCR (except PDC calls, see below).

PDC

The LCR function also includes handling of the PDC (Public Destination access Code) which is mainly used in the US as a complement to the LAC. When using a PDC the call is not least cost routed, but external numbers may be (selectively) barred for calls by using the LCR features, Toll restriction and Forced account code. A comparison to help understanding PDC:

To use only basic routing (no LCR), the user dials a standard access code to the public network and the dialled number is sent for external analysis. Toll restriction and Forced account code cannot be used since they are LCR features.

A basic route access code is initiated with the number type ED.

To use LCR, the user dials a LAC and the dialled number is modified, is Toll restricted etc.,

Note: If the program unit that handles the feature Time of day is loaded, least cost time zone data must be initiated. It may be transparently initiated though, if the feature is unwanted.



before the modified number is sent to external analysis.

An LAC is initiated with the number type LC.

To use LCR with PDC , the user dials a PDC and the dialled number is LCR-analysed, but only Toll restriction and Forced Account Code are applied on the call. The dialled number is not modified before it is sent to external analyses.

A PDC is initiated with the number type PD.

No other LCR feature, e.g. Time of day, than the two mentioned above may be applied to a PDC call.


Initiate the numbers and number type for LCR using the command NANSI :

NANSI :NUMTYP=LC,NUMSE=9; The number series 9 as LAC is used in US-like numbering plans.

NANSI :NUMTYP=LC,NUMSE=00; The number series 00 as LAC is used in other numbering plans.

Group the numbers/number series that shall be routed the same way, both regarding primary and alternative routing. Create fictitious external destinations, one for each group, and initiate them with number type ED.

For the examples below 0120 to 0125 are chosen to be used as fictitious destinations:

NANSI :NUMTYP=ED,NUMSE=0120&&0125;

Initiate primary and alternative routing choices with command RODDI for the fictitious destinations initiated above. Consider how to modify the number before sending it to the route, the fictitious destination (or part of it) is usually truncated. It is also possible to prefix the number here.

RODDI :DEST=0120,ROU=... etc.

Initiate the number series and number type for the PDC.

For the example below the number series 01 is selected:

NANSI :NUMTYP=PD,NUMSE=01; This call barring is further described below in Example 3, exception number using PDC in the section DNT - Destination Number Table. The number series 01 was randomly chosen.

7.11.3 Execution

7.11.3.1 ENT - External Number Table

The ENT is primarily used to translate external numbers to private network numbers, mainly for off-net to on-net routing. For the US market the ENT can also be used to distinguish between conflicting



numbers using a timer called critical timing.

ENT has the ability to analyse the first 16 digits of a dialled number. If the number is found in the ENT the number is translated into a new dialled number. This is the only feature in the system that can achieve this. The unique thing is that the translation results in another dialled number, which means that the number analysis will start all over again for this translated number.

The table is not mandatory and if the dialled number is not found in the ENT the analysis proceeds to the next table, the NLT.

Off-net to On-net routing

If a user dials the public number to an extension within the own private network this public number shall be translated to the corresponding private number within the private network. The ENT is for this case set up to detect number series within the own private network. A number series where all numbers shall be converted the same way (using TRC and PRE) is handled by one ENTRY.

LCDDI :TAB=ENT,ENTRY=0008422,TRC=6,PRE=850; The user dials 0008422... where 00 is the LAC (least cost routing access code), 08 is the trunk code (area code), and 422... is the subscriber number in the public numbering plan. Since this is an extension within the own private network the ENT shall be used to convert this public number into the corresponding private network number, so that the call is routed within the own private network.

When the number 0008422 is detected, the system immediately truncates the first 6 leading digits, leaving the 2 which is the first digit of the extension number within the exchange where the extension is situated. The number is then prefixed with 850 which is the location code to the exchange (where the extension is situated) within the own private network.

Translation to internal numbers

If a user dials the public number to an extension within the own exchange this public number shall be translated to the corresponding directory number within the own exchange. The ENT is for this case set up to detect number series within the own exchange. All numbers in a number series that can be converted the same way (using TRC and PRE) is handled by one ENTRY.

LCDDI :TAB=ENT,ENTRY=00422,TRC=4; The user dials 00422... where 00 is the LAC (least cost routing access code), and 422... is the subscriber number in the public numbering plan. Since this is an extension within the own exchange the ENT shall be used to convert this public number into the corresponding internal number.

When the number 00422 is detected, the system immediately truncates the first 4 leading digits, leaving the 2 which is the first digit of the extension number in the own exchange.

Translation of special numbers

The ENT can also be used for translation of special (single) numbers to internal (or external) extension numbers. In this case the ENT is used to translate the dialled number into a completely different number, i.e. the whole number is replaced. An example for the US application is the emergency number 911. If the destination of the emergency number is located within the own exchange (e.g. hotel, mall or campus police), the emergency number is translated into the corresponding internal number and the call is routed to this extension in the own exchange.



LCDDI :TAB=ENT,ENTRY=911,TRC=3,PRE=11401; When the number 911 is detected it is immediately translated into the internal number 11401.

Conflicting numbers

For the US market the ENT offers basic analysis of conflicting numbers. An example in the US numbering plan is operator assistance. It shall be possible to select different public operators by dialling either 90 or 900. (9 is the LAC, 0 and 00 are the different operators.)

In a conflict situation like this, a timer called critical timing is used in order to determine whether another digit is dialled or not. (Was 90 dialled, or will 900 be dialled?) The timer is started when the number initiated in the ENT is detected. If another digit is dialled within the critical time, the analysis immediately proceeds to the next table. If no more digits are dialled within the critical time, the dialled number is transformed according to the data (TRC/PRE) assigned to that number in the ENT table.

LCDDI :TAB=ENT,ENTRY=90,TRC=2,PRE=24000,CONF=Y; The number 90 (ENTRY=90) is initiated as a conflict number (CONF=Y), if no more digits are dialled after 90 the number is translated according to the assigned TRC and PRE data:

Firstly two digits are truncated from the dialled number (TRC=2), which in this case means truncation of the digits 90.

Secondly the digits that are left (in this case there are no digits left) are prefixed with 24000 (PRE=24000), which in this case means prefixing nothing with 24000.

The result is that the dialled number 90 is transformed into 24000. The call will once again go through number analysis, but this time with 24000 as dialled number. (In this example the number 24000 is some kind of PABX operator within the own exchange).

7.11.3.2 NLT - Number Length Table

The NLT shall be used when an exchange has a remote LIM in a different area (other area code).

This table can be used also in branch office scenarios where an exchange in main site has IP phones in the branch offices located in different areas (other area code).

For the US market the NLT can also be used to distinguish between conflicting numbers using a combination of timer and number length analysis.

The table is not mandatory and if the dialled number is not found in the data base the analysis proceeds to the next table, the DNT1.

Area code prefixing

If an exchange consists of LIMs (remote LIM) situated in different areas (with different area codes), a dialled local public number intends to address different public subscribers depending on in which LIM the number is dialled.

When IP telephony is used in a branch office scenario, it is possible to have branch offices served by



IP extensions that are registered in the main site exchange. Branch offices are represented by domains to which the IP extensions are associated. Therefore, and similarly to the remote LIM case, a dialled local public number intends to address different public subscribers depending on in which branch office the number is dialled.

An example: A call to the local public number 20802 from a LIM/domain that is situated in the area code 0455, has to be separated from a call to the local public number 20802 from a LIM/domain that is situated in the area code 0451. When the caller dials only the local public number 20802 (without the area code) this information is not enough to route that call correctly, the exchange that the LIMs/domains belong to cannot see that the calls originated in different area codes. To solve this the dialled number must be modified to also include the area code of the originating LIM/domain before routing the call.

As there can be different domains associated to the same LIM, in the case the originator is an IP extension, the domain area code prevails over the LIM area code, i.e. if set, domain area code is used instead of the LIM area code to modify the dialled number.

It is strongly recommended not to use customer numbers (parameter CUST in command RODDI ) to indicate what LIM or IP extension the call originated in, and then use this information to control the routing of the call. Instead, the NLT shall be used to insert the LIMs/domains own area code between the LAC and the subscriber number of the dialled local public number, i.e. all dialled local public numbers shall be translated into national format. Then there is no need to treat calls differentlydepending on which LIM/domain the call originated in when breaking out to the public network. The number will always be in national format and thus uniquely define called subscriber, no matter what area code the call originated in.

If the call is to be routed within a private network, the routing shall be set up to always forward the dialled number including LCR access code and trunk code (area code) to the next exchange in the private network.

The area code flag, ACF, shall be set to Y (as in Yes) to indicate that a dialled number shall be prefixed with own area code:

LCDDI :TAB=NLT,ENTRY=002,.............,ACF=Y; All public numbers beginning with digit 2 (in this example public numbers beginning with digit 2 can only be to local public destinations) will be prefixed with own area code.

LCLDI :LIM=x,........,AC=0455; The own area code for LIM x is initiated with the LCLDI command, in this example the AC is 0455.

IPGDI :DOMAIN="z",LIM=x,........,AC=0477; The own area code for domain "z", which belongs to LIM x is initiated with the IPGDI command, in this example the AC is 0477.

The result is that the dialled local public number 002... is modified into 0004552... if it originates in LIM x and the originator is not an IP extension that belongs to domain "z".

And it is modified into 0004772... if it originates in domain "z".

This initiation must of course be done for all LIMs and domains in the exchange, with their respective area codes.

In a branch office scenario, the initiation of domain area codes for the branch offices requires of



course the initiation of a LIM area code for all LIMs in the main site exchange in order to keep consistency between IP and non IP extensions.

Conflicting numbers

For the US application the NLT also offers extended analysis of conflicting numbers.

In the US numbering plans a complete public number consists of 10 digits:

The first three digits represents the area code (AC).

The following three digits represents the office code (OC).

The last four digits represents the subscriber number.

The length of the public number is 3+3+4=10 digits. Add the LAC (9) and the total length will be 11 digits.

The shape/pattern of the ACs and the OCs are specific, but when interchangeable ACs or OCs are introduced conflict may occur.

Below is an example where the number 525-2591 either can be a complete number in own area:

525 is the OC

2591 is the subscriber number

The total length of the dialled number (including the LAC) will be 8 digits.

or a long distance number:

525 is the AC

259 is the OC

1 is the first digit of four in the subscriber number.

The total length of the dialled number (including the LAC) will be 11 digits.

To be able to distinguish between these two cases a timer is used to decide when the whole number is dialled, and then the length of the number is analysed. The concluded number length is used by the system in the further handling of the call.

When initiating the number the parameter MIN shall state the total length of the number in the own area, i.e. 8 digits. The parameter MAX shall state the total length of the long distance number, i.e. 11 digits.

LCDDI :TAB=NLT,ENTRY=95252591,CONF=Y,MIN=8,MAX=11; The number 95252591 is initiated as a conflict number, with two possible lengths, 8 or 11 digits.

After the number length has been determined to either of the two, the call will proceed to a DNT where the number will be transformed etc.

The number length analysis can also be combined with the insertion of own area code. In this case



the insertion of own are code takes place if the length of the dialled number is the same as the length initiated in the parameter MIN. If more digits are dialled the area code is not inserted.

LCDDI :TAB=NLT,ENTRY=95252591,CONF=Y,MIN=8,ACF=Y; The number 95252591 is initiated as a conflict number, when this number is dialled the own area code is inserted. If more digits are dialled own area code is not inserted and the call proceeds to a DNT for further analysis.

7.11.3.3 DNT - Destination Number Table

The DNTs are where the main least cost routing takes place. Instead of letting the dialled number address a destination data record (command RODDI ) directly into a fictitious destination that address a destination data record the dialled number is modified in the DNT and FDT.

Different dialled numbers that are to be routed the same way, are transformed into the same fictitious destination. Several entries in each of the DNTs are possible, but since many of them will be transformed into the same fictitious destination they will address the same destination data records. This means that LCR will only use some of the 2500 destination data records available (that has to be shared with basic routing and PNR). This is how LCR increases the capacity of external analysis.

Dialled number 1 is 9-009-46-8-90510 Dialled number 2 is 9-009-47-31-244061

Without LCR: (One dialled number addresses one destination data record)

With LCR: (Two totally different dialled numbers address the same destination data record)

Figure 7-11. Use of destination data records without LCR



The savings are perhaps even more obvious if one consider that there may be alternative choices for each destination. For example, if five different numbers (that are to be routed the same way) are initiated with five routing choices each, not using LCR, will require 25 destination data records, while only five destination data records are sufficient if LCR is used.

As can be seen in the figure above there is the possibility to prefix both in the DNT and the FDT. The prefix in the DNT may be used for transit network selection. One example in the US is AT&T that have 288, in Sweden Tele2 have 007. See example 2 below.

Furthermore there is the possibility to prefix in the destination data record. This is when the number needs to be transformed differently for different route choices. By using truncation (parameter TRC), prefixing (parameter PRE), and start digit sending (parameter SRT), the number may be modified in all possible ways.

First the PRE in the DNT is applied, then the PRE in the FDT, and lastly the PRE in the destination data record.

The DNT1 and the DNT2

A destination number may be analysed in either of two levels of depth. The DNT1 table analysis 16 digits depth which is good for analysing exception numbers (since ENTRY then must comprise the whole number). The DNT2 table analysis 8 digits depth and is used for number series.

First the dialled number is modified according to the assigned TRC and PRE data ( LCDDI :TAB=DNTx,ENTRY=,TRC=,PRE=).

Figure 7-12. Use of destination data records with LCR



Secondly, an entry in the DNT tables must have a Fictitious Route Choice Table (FRCT) initiated. The FRCT is not a table but an index to the Fictitious Destination Table (initiated with LCDDI :TAB=FDT) where a prefix is found.

The prefix in the FDT is used for prefixing the previously modified number.

The result is a fictitious destination to be analysed, i.e. since it is an external destination it will address a destination data record (a DEST initiated with RODDI ).

Example 1, basic LCR

The number series in this example is 9 009 46 8, where the digit 9 is the least cost routing access code (LAC), 009 is the international prefix, 46 is the country code to Sweden, and 8 is the trunk code for Stockholm. This number shall be initiated in the number table, DNT2, with the appropriate data for addressing a fictitious destination.

Start with creating a fictitious destination to be used for outgoing calls to Stockholm. (In this example the destination used is 0120.) Initiate the FDT that shall prefix the dialled number (that previously was modified in a DNT) so that it addresses the above fictitious destination:

LCDDI :TAB=FDT,PRE=0120,FRCT=22; Any entry in a DNT that refers to FRCT=22 will be prefixed with 0120.

Initiate the number series with appropriate data regarding the above:

LCDDI :TAB=DNT2,ENTRY=9009468,TRC=1,FRCT=22; The leading digit 9, in the number 9 009 46 8 is truncated. The modified number will be 009 46 8.

After that, the FRCT=22 indexes the FDT where the prefix 0120 is found. The result is that the dialled number 9 009 46 8 is transformed into 0120 009 46 8, where the digits 0120 is the fictitious destination used to address a destination data record (initiated with RODDI :DEST=0120,..).

The same FRCT may be used by other modified numbers. The result is that calls to different external destinations are now calls to one and the same fictitious destination.

Example 2, basic LCR with transit network selection

If different transit networks are wanted for different numbers that are to use the same FRCT, the PRE in the FDT is used. For example, if AT&T transit network is wanted for calls to Stockholm, Sweden, the number shall be prefixed with 288 in the DNT.

LCDDI :TAB=DNT2,ENTRY=9009468,TRC=1,PRE=288,FRCT=22; The leading digit 9, in the number 9 009 46 8 is truncated, and after that the number is prefixed with 288. With the prefix 0120 in the FDT the result will be the number 0120 288 009 46 8.

Example 3, exception number using PDC

An exception is a number within a series, that is barred from calling to. The barring is controlled in the toll restriction on a per category basis. With Forced account code which is set per extension, the barring may be further refined (parameter ROC in command EXTEI , KSEXI , DTEXI ), and this is also valid for generic extensions.



Exceptions may be initiated using LAC or PDC. In this example PDC is used. The PDC make use of the LCR tables, but only Toll restriction (and Forced account code) is used. No least cost routing will take place.

Initiate the number series as in the examples above, but using the PDC=01 instead of the LAC=9.

LCDDI :TAB=DNT2,ENTRY=01009468,FRCT=X;

The number in this number series that shall be barred from calling to is the number to the speaking clock . This number is 90510 in Sweden. The complete number 01 009 46 8 90510 is put in the exceptions table (DNT1) and is thereby barred/open for users, as stated in the parameter TOLL (toll restriction).

Toll restriction is a bit map table containing whether a TCD category is allowed or barred from calling a number stated in the DNT1 or DNT2. The toll restriction is set in the parameter TOLL in the DNTs, each bit in TOLL refers to a corresponding TCD category (0-14).

If the parameter TOLL is omitted all categories are allowed to call the stated destination, i.e. all bits in the TOLL bit map are by default set to 1.

LCDDI :TAB=DNT1,ENTRY=0100946890510,FRCT=X,TOLL=000000000000000; Users of all TCD categories are barred from calling the speaking clock in Stockholm, Sweden.

Unlike in Example 1, basic LCR the dialled number will not be transformed according to the data in the DNT and FDT. In this example a PDC is used, and the dialled number is sent for external analysis.

Example 4, time of day

If the Time of day function is to be used, the parameter TZONE shall also be set when initiating the FDT table. By using time of day, different fictitious destinations may be addressed depending on the time zone.

LCDDI :TAB=FDT,FRCT=22,PRE=0120,TZONE=1; LCDDI :TAB=FDT,FRCT=22,PRE=0123,TZONE=4;

If a call is made during the time period represented by time zone 1 the number will be prefixed with 0120. Likewise, a call during time zone 4 will be prefixed with 0123.

The time zones are initiated with the LCTDI command. Further information on the LCTDI command can be found in the command description for LEAST COST ROUTING, TIME OF DAY , LC.

Example 5, dialled number retrieval

Dialled number retrieval can be utilized if it is required that two or several different public numbers shall address the same destination data record.

Dialled number retrieval is indicated by the value 3 in D 16 in the ADC parameter in the RODDI command.

RODDI :DEST=..., ADC=xxxxxxxxxxxxxxx3xxxxxxxxxx;



When the value 3 is detected in the ADC parameter the external number to use is composed by the destination code assigned for the route choice, together with the public part of the dialled external number.

7.12 Loop avoidance/Transit counter General

-

Prerequisites

Loop avoidance is used in APNSS/DPNSS networks.

Transit counter is used in ISDN and H.323 networks.

Execution

The maximum number of transit exchanges a call can be routed through in order to reach the final destination is set in D 14 and D 15 of the ADC parameter in the command RODDI .

7.13 MCT - Malicious call tracing General

Three variants of MCT exist: the simplified (Saudi), MCT for ISDN and MCT for CCSS7.

Prerequisites

Use of analogue lines also requires an effort in the PSTN.

Execution

Set D 10 =1 in the SEL parameter of the command ROCAI (or ROCAC ) to enable MCT on the stated route.

If it is a CCSS7 route also set D 7 =1 in the VARI parameter of the command RODAI to enable MCT on the stated route.

7.14 PNR - Private network routing

7.14.1 General

PNR is used for routing of outgoing external private network calls i.e. calls terminating in the own private network. The function is the same as with basic routing, but PNR enables a lot more destinations to be stated as entry to routing.

In addition to this, PNR enables each destination to have two route choices with enhanced number translation. One route choice can have a PRE of maximum 10 digits, and the other a PRE of



maximum 16 digits. This is often sufficient for routing through the public network.

This means that the system is able to handle much bigger numbering plans by using PNR.

In the figure below is an example of the use of PNR for routing through different networks.

PNR structure

PNR is basically a preprocessor to the existing basic routing software. The pre-process consists of two tables where the dialled number leads to a prefix, which in turn addresses a Route Choice Table (RCT). Basic routing uses the dialled number directly to address an RCT.

An RCT is all the route choices for a (fictitious) destination. Each route choice uses one destination data record. The route choices are initiated with the command RODDI .

The first PNR table is the PNR Destination Number Table (PR DNT). This is a table with 1500 entries where an entered destination (parameter ENTRY) will result in an index (parameter FRCT) to the next table, the fictitious RCT. Also the enhanced number translation data are stored in the PR DNT, two sets per destination.

The prefix stored in the fictitious RCT is used to address an RCT. The prefix is used by itself as a destination, it is not used for prefixing.

The purpose of the fictitious RCT is to restrict the addressing of the RCTs.

The purpose with restricting the addressing of the RCTs is that RCTs are taken from the common pool of 2500 destination data records that PNR shares with LCR and basic routing. An RCT may consist of up to 8 linked route choices, where each route choice uses one destination data record ( RODDI :DEST=,CHO=).

With PNR, one RCT may be used by many entries in the PR DNT. Because of this possibility of efficient utilization of the RCTs there should be enough destination data records for all (PNR, LCR and basic routing) if the PNR-configuration (and LCR-configuration) is well planned. This will be shown in the examples below.

1. is the ordinary route choice in the private network. 2. is an alternative route choice through a public network (PSTN). 3. is an alternative route choice through another network.

Figure 7-13. Example of how PNR can be used to choose the best available route



The PNR data tables are administered by the command group LC and data is set, deleted or printed using the LCDDI /E/P commands where the parameter TAB is set to either PNR or RCT.


Initiate the external destination number series using the command NANSI :

Figure 7-14. An overview of the PNR data tables



NANSI :NUMTYP=ED,NUMSE=85024; NANSI :NUMTYP=ED,NUMSE=85040; These external destination numbers will be used to address the PNR access code in the PR DNT.

If the market dependent parameter (MDP) NONADESTCHECK is set to Check is made, the prefix in the fictitious RCT must be initiated as an external destination number. This MDP states if the destination is to be checked in the number analysis or not.

NANSI :NUMTYP=ED,NUMSE=0123; This external destination number is used by PNR to address an RCT. It is necessary to initiate it in the number analysis in order to be able to initiate it as a destination in the external analysis.

Initiate the external destination number series for PSTN access using the command NANSI :

NANSI :NUMTYP=ED,NUMSE=00; This external destination is required for overflow to the PSTN, when the dialled number is translated into a public number.

Outgoing routes must be assigned. In the following examples ROU=50 is a tie line route and ROU=20/30 are public external line routes.

7.14.3 Execution

Example 1, initiation of a tie line route

Initiate a route between the location Karlskrona (KA) and the locations Bollmora (BO) and Sundbyberg (SG). (HF is Huvudfabriken, a transit exchange near BO/SG.) The route in this example is a single tie line route.

Initiate the PNR access code for BO and SG. The same FRCT may be used for both BO and SG as they are both reached using the same route. Using the same FRCT means that they will share the same RCT. FRCT may be assigned any value between 1 and 64, X is used in this example.

LCDDI :TAB=PNR,ENTRY=85024,FRCT=X; LCDDI :TAB=PNR,ENTRY=85040,FRCT=X;

Result:

Table 7-1 PR DNT - PNR Destination Number Table



Initiate the data in position X in the fictitious route choice table for PNR. The digits 0123 are used as prefix (external destination).

LCDDI :TAB=RCT,FRCT=X,PRE=0123;

Result:

Initiate the RCT in the external analysis.

RODDI :DEST=0123,ROU=50,SRT=5; The SRT value depends on how the numbering plan in the network is set up. If the composed number is passing a transit exchange, the whole number may be sent, and the decision of the further routing is made in that same transit exchange.

Result:

Now the single tie line route between KA and BO/SG is initiated. If the user dials 85024 or 85040 followed by the extension number, the system will select route 50 for the completion of the call. The digits sent to the co-operating exchange will be either 24xxx or 40xxx.

ENTRY PRE TRC PRE TRC FRCT 85024 X 85040 X

Note: RCT in the LCDDI command is only used as a parameter to distinguish this table from the other tables handled by the LCDDI command.



Example 2, initiation of an alternative route

Add a public alternative to the single tie line route between the location Karlskrona (KA) and the locations Bollmora (BO) and Sundbyberg (SG).

In this case the private numbers 85024 and 85040 will be translated individually.

The national public directory number for Bollmora is 08-682xxxx and for Sundbyberg 08-764xxx, where 08 is the area code and the following digits is the subscriber number (location code + directory number).

Add an alternative RCT. No editing information (PRE/TRC) is assigned with RODDI , instead a flag in the route choice indicates that this information will be found in the PNR destination table, under the PNR access code that was used to address the present RCT. The flag is: D 16 is set to 1 in the ADC parameter. The 1 also refers to set 1 in the PR DNT.

RODDI :DEST=0123,ROU=50,SRT=5; (initiated earlier) RODDI :DEST=0123,ROU=30,SRT=3,CHO=1,ADC=00000000000002510000000000;

Result:

Update the PNR access code with the individual number translation information (set 1) for the BO and SG locations.



LCDDI :TAB=PNR,ENTRY=85024,FRCT=X,TRC=3,PRE=000868; LCDDI :TAB=PNR,ENTRY=85040,FRCT=X,TRC=3,PRE=000876;

Result:

Now the public choice is initiated. With alternative routing the route 30 is selected. The number translation information is found in the PR DNT (set 1) as indicated by D 16 in the ADC parameter.

If the user dials 85024/85040 followed by an extension directory number, and meet congestion at the ordinary choice, the system selects route 30 for completion of the call. The digits sent out to the co-operating exchange will be either 08682xxxx or 08764xxxx as indicated by set 1 of individual number translation information.

Example 3, initiation of a second alternative route

Add a second alternative to the single tie line route between the location Karlskrona (KA) and the locations Bollmora (BO) and Sundbyberg (SG).

In this example a second set of individual number translation data is assigned to the private numbers 85024 and 85040. As there is no second network between KA and BO/SG in real life, the symbolic national PDN NNNNNN is used in this example.

Add a second alternative RCT. No editing information (TRC/PRE) is assigned with RODDI , instead a flag in the route choice indicates that this information will be found in the PNR destination table, under the PNR access code


ENTRY PRE TRC PRE TRC FRCT 85024 000868 3 X 85040 000876 3 X



that was used to address the present RCT. The flag is: D 16 is set to 2 in the ADC parameter. The 2 also refers to set 2 in the PR DNT.

RODDI :DEST=0123,ROU=50,SRT=5; (initiated earlier) RODDI :DEST=0123,ROU=30,SRT=3,CHO=1,ADC=xxxxxxxxxxxxx251xxxxxxxxxx; (initiated earlier) RODDI :DEST=0123,ROU=20,SRT=3,CHO=2,ADC=xxxxxxxxxxxxx252xxxxxxxxxx;

Result:

Update the PNR access code with the individual number translation information (set 2) for the BO and SG locations.

LCDDI :TAB=PNR,ENTRY=85024,FRCT=X,TRC=3,PRE=000868,TRC1=N,PRE1=NNNNNN; LCDDI :TAB=PNR,ENTRY=85040,FRCT=X,TRC=3,PRE=000876,TRC1=N,PRE1=NNNNNN;

Result:


ENTRY PRE TRC PRE TRC FRCT 85024 000868 3 N X 85040 000876 3 N X



Now the second choice is initiated. With alternative routing the route 20 is selected. The number translation information is found in the PR DNT (set 2) as indicated by D 16 in the ADC parameter.

If the user dials 85024/85040 followed by an extension directory number, and meet congestion at both the ordinary choice and the first alternative choice, the system selects route 20 for completion ofthe call. The digits sent out to the co-operating exchange will be either NNNNNNxxxx or NNNNNNxxxx as indicated by set 2 of individual number translation information.

7.15 Semipermanent connections with D over B signalling

7.15.1 General

Semipermanent connections are available in some public networks, as a cost effective alternative to expensive leased lines.

In this application the public network is used as a transparent carrier of information such as voice, data and supplementary services with the same functionality as for DPNSS in a private network.

A number of digital channels will be permanently connected from one digital PABX interface, via the public network, to another digital PABX interface for use as an inter PABX tie line. Those channels not used as semipermanent connections can still be used for normal circuit switched calls over the digital interface to the public network.

7.15.2 D over B signalling

D over B is used with semipermanent connections, to form a tie line with DPNSS functionality between ASB 501s via a public network.

To achieve this a digital interface is required between the PABXes and the public network.

The signalling for call control and interface maintenance is normally carried out on a dedicated time slot in the digital interface (i.e. time slot 16 is used for signalling in a 30B+D digital interface). The B-channels are the transmission channels for voice and data while the D-channel is used for signalling.

The public network does not support the signalling protocol used by the PABX. This problem is solved by having one of the B-channels (normally carrying speech) to carry the signalling information. This channel is called the D over B channel .

7.15.3 Configuration

7.15.3.1 Software

TL58

TL58 uses CCS according to APNSS specifications, providing the same functionality as DPNSS.

TL30



Handles the initiation of the digital CAS interface. The first individual initiated on the digital interface, is assigned towards TL30. This individual will serve as the D over B -channel. The rest of the individuals in the route, are assigned towards TL58. These channels will serve as the B-channels.

TL/SL (ISDN)

Handles the initiation of the digital CCS interface. The first individual initiated on the digital interface, is assigned towards the SL. This individual will serve as the D-channel. The remaining channels within the route, are assigned towards TL58. These channels will serve as B-channels.

7.15.3.2 Hardware

SLU - Signalling Line Unit

The Signalling Line Unit is the hardware interface between the TL58 and a switched mode synchronous modem. The signalling is done over a V.24 connection from the SLU to the modem. (SLUs are only for sustaining).

Modem

The semipermanent connection application requires a 2-wire switched mode synchronous modem. The modem operates in full duplex mode.

The modem is connected to an ordinary analogue extension line unit (ELU) that is initiated as a special extension (command SPEXI ).

The modem is controlled by the Data Terminal Ready (DTR) circuit of the V.24 interface. When DTR goes high the modem goes off hook, thereby initiating a hot-line call to the individual serving as the D over B -channel.

TLU-D CAS

Serves as the digital CAS interface and is a 30/32-channels digital PCM board, operating at 2 Mbits/s.

TLU-D CCS

Serves as the digital CCS interface and is a 30B+D digital PCM board, operating at 2 Mbits/s.



ELU-A = analogue ELU TLU-D = digital TLU

7.15.4 Procedure

When initiating semipermanent connections with D over B signalling this order must be followed:

Figure 7-15. Semipermanent connection setup

Figure 7-16. A digital interface for semipermanent connections

Three speech channels and one signalling channel

1 Initiation of the D over B -channel (Signalling) 2 Initiation of the hot-line connection ELU-TLU 3 Initiation of B-channels (Speech)



Removal of a semipermanent connection with D over B signalling is done in the opposite order.

7.15.5 Execution

The execution is described using two examples:

7.15.5.1 Example with CAS interface

Prerequisites

Configuration of the ASB 501 using TLU-D CAS is made according to figure 7-15.

Software: TL58 and TL30.

Hardware: SLU1, Modem LM Ericsson ZAT 2400/2400-7, ELU-A, TLU-D CAS.

The modem must be set up according to strapping instructions for MODEM LM ERICSSON ZAT 2400/2400-7 FOR APNSS.

Command handling

Initiation of a D over B -channel, CAS:

TLU-D CAS board position: 1-1-10 (using individual 01)

ROCAI :ROU=7,SEL=011000000000001,SERV=0010000000,SIG=011111000000, TRAF=00151515,TRM=5,DIST=5,DISL=128,BCAP=101100; RODAI :ROU=7,TYPE=TL30,VARC=00000021,VARI=00000151,VARO=00000001; ROEQI :ROU=7,TRU=1-1,EQU=1-1-10-01; RODDI :DEST=007,ROU=7,SRT=4;

Initiation of the hot-line connection ELU-TLU:

ELU-A board position: 1-0-10 (using individual 0)

EXTEI :DIR=2011,EQU=1-0-10-0,CAT=1,TYPE=EL6; SPEXI :DIR=2011,OPT=N,NDC=007;

Initiation of 3 B-channels:

TLU-D CAS board position: 1-1-10 (using individuals 02 to 04) SLU1 board position: 1-1-00 (using individuals 1 to 3)

ROCAI :ROU=9,SEL=011000000000001,SERV=0010000000,SIG=011111000041, TRAF=00151515,TRM=7,DIST=5,DISL=128,BCAP=101100; RODAI :ROU=9,TYPE=TL58,VARC=00000311,VARI=00000000,VARO=00000000; ROEQI :ROU=9,TRU=1-1,EQU=1-1-10-02,SQU=1-00-1; ROEQI :ROU=9,TRU=1-2,EQU=1-1-10-03,SQU=1-00-2;

1 The first example is when a CAS digital interface is used. 2 The second example is when a CCS digital interface is used.



ROEQI :ROU=9,TRU=1-3,EQU=1-1-10-04,SQU=1-00-3; RODDI :DEST=009,ROU=9,SRT=4;

To get the semipermanent connections up and running, the procedure above must be repeated in the PABX that is to be the other node in the semipermanent connections setup. This will be the result:

D over B -channel multiple pos : 1-1-10-1 B-channel #1 multiple pos : 1-1-10-2 B-channel #2 multiple pos : 1-1-10-3 B-channel #3 multiple pos : 1-1-10-4

7.15.5.2 Example with CCS interface

Prerequisites

The configuration of the ASB 501 using TLU-D CCS is made according to figure 7-15.

Software: TL58, TL/SL (ISDN).

Hardware: SLU1, Modem LM Ericsson ZAT 2400/2400-7, ELU-A, TLU-D CCS.

The modem must be set up according to strapping instructions for MODEM LM ERICSSON ZAT 2400/2400-7 FOR APNSS.

Command handling

Initiation of a D over B -channel, CCS:

The procedure above must be repeated in the PABX that is to be the other node in the semipermanent connections setup. This will be the result: TLU-D CCS board position: 1-1-60 (using individual 01)

ROCAI :ROU=8,SEL=011000000000001,SERV=0010000000,SIG=011111000031, TRAF=00151515,TRM=5,DIST=5,DISL=128,BCAP=101100; RODAI :ROU=8,TYPE=SL60,VARC=00000640,VARI=00000000,VARO=00500000; ROEQI :ROU=8,TRU=1-1,EQU=1-1-60-01; RODDI :DEST=008,ROU=8,SRT=4;

Initiation of the hot-line connection ELU-TLU:

ELU-A board position: 1-0-10 (using individual 1)

EXTEI :DIR=2012,EQU=1-0-10-1,CAT=1,TYPE=EL6; SPEXI :DIR=2012,OPT=N,NDC=008;

Initiation of 3 B-channels:

TLU-D CCS board position: 1-1-60 (using individual 02 to 04) SLU1 board position: 1-1-00 (using individual 1 to 3)



ROCAI :ROU=10,SEL=011000000000001,SERV=0010000000,SIG=011111000041, TRAF=00151515,TRM=7,DIST=5,DISL=128,BCAP=101100; RODAI :ROU=10,TYPE=TL58,VARC=00000413,VARI=00000000,VARO=00000000; ROEQI :ROU=10,TRU=1-1,EQU=1-1-60-02,SQU=1-00-1; ROEQI :ROU=10,TRU=1-2,EQU=1-1-60-03,SQU=1-00-2; ROEQI :ROU=10,TRU=1-3,EQU=1-1-60-04,SQU=1-00-3; RODDI :DEST=010,ROU=10,SRT=4;

To get the semipermanent connections up and running, the procedure above must be repeated in the PABX that is to be the other node in the semipermanent connections setup. This will be the result:

D over B -channel multiple pos : 1-1-60-1 B-channel #1 multiple pos : 1-1-60-2 B-channel #2 multiple pos : 1-1-60-3 B-channel #3 multiple pos : 1-1-60-4

8 Termination If exchange data are changed, a dump to the backup media must be performed.



Administration of Routes in MD110

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