Chapter 10 - Networking ........................................................................................10-2

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LZU 108 1643 R1A OPERATION AND MAINTENANCE BC9 LEVEL 1 10-1

Chapter 10 - Networking ........................................................................................10-2

Introduction......................................................................................................................10-2 Centralised operator...................................................................................................................... 10-3

CAS and CCS ...................................................................................................................10-3 CAS - Channel Associated Signalling .......................................................................................... 10-4 CCS - Common Channel Signalling ............................................................................................. 10-5

DPNSS - Digital Private Network Signalling System ...................................................10-5

ISDN - Integrated Services Digital Network .................................................................10-7

Definitions and concepts..................................................................................................10-9 Numbering plan ............................................................................................................................ 10-9

Open numbering plan ............................................................................................................... 10-9 Closed numbering plan........................................................................................................... 10-10 Mixed numbering plan............................................................................................................ 10-10

Routes, trunks, lines and directions ............................................................................................ 10-10 Definitions .................................................................................................................................. 10-12

Initiation of routes..........................................................................................................10-13 The ROCAI (Route Category Initiate) command ....................................................................... 10-14 The RODAI (Route Data Initiate) command.............................................................................. 10-16 The ROEQI (Route Equipment Initiate) command .................................................................... 10-17 The RODDI (Route External Destination Data Initiate) command ............................................ 10-17

Alternative routing.................................................................................................................. 10-19 Example of a Direct In Dial route............................................................................................... 10-20 Initiation of an ISDN route......................................................................................................... 10-20

Parameters for exchange A..................................................................................................... 10-20 Parameters for exchange B ..................................................................................................... 10-21 Network synchronisation ........................................................................................................ 10-22 Explanation of the parameters ................................................................................................ 10-23

Parameter SEL.................................................................................................................... 10-23 Parameter SIG .................................................................................................................... 10-23 Parameter TRAF................................................................................................................. 10-23 Parameter SERV................................................................................................................. 10-24 Parameter TRM .................................................................................................................. 10-24 Parameter BCAP ................................................................................................................ 10-24 Parameter TYPE................................................................................................................. 10-24 Parameter VARI ................................................................................................................. 10-24 Parameter VARO................................................................................................................ 10-25 Parameter VARC................................................................................................................ 10-25 Parameter ADC................................................................................................................... 10-25

Questions.........................................................................................................................10-26

Exercises..........................................................................................................................10-26

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Chapter 10 - Networking Normally the MD110 would not be found isolated with only internal traffic, there would be some way of communicating with the external telephony systems. This chapter describes some signalling systems used for external communication.

Introduction The MD110 can not only set up a normal call between two users in the own exchange, it also has the possibility to communicate with other exchanges. When connecting the MD110 to external nets, there is a large number of things to think about e.g. are we connecting with older analogue or newer digital channels, do the exchanges share functions between themselves. A public exchange is what a normal subscriber uses to communicate with other, it is often quite limited in the number of services available and not very cheap for distance calls. By connecting private owned exchanged it is possible to share functions other the net and most often much cheaper. A private network consists of PABXs connected in a net. This net is usually connected to the PSTN (Public Switched Telephone Network). The private network can provide many functions, not available in the PSTN, to its users. It is important to remember that, if the exchanges shall transfer functions they have to use the same communication protocol in the whole network, no transfer between protocols.

PSTN

Private Network

Figure 10.1: Private network connected to the PSTN.

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Centralised operator Centralised operator is an example of one of the services a private network can supply to its users. This function means that a PABX-operator or a PABX-operator group, in addition to his/her/their own exchange, can serve several sub-exchanges in a private network. These sub-exchanges lack local PABX-operator consoles, but can have lines directly to/from the public network. If a local PABX-operator exists, calls will be routed there first, not to a centralised operator.

The basic functions are:

� Day/night status message, that gives the operation status of an exchange is sent to exchanges that are members of the private network.

� Rerouting to another PABX in the for day- or night service switched exchange and transmission of information relevant to the call in question to the centralised PABX-operator.

For each exchange in the network, four alternative answering positions can be specified. If the operator positions are not manned in the local exchange, incoming calls will automatically be routed according to a pre-programmed table.

PSTN/ISDN

Night service position(Last choice)

2nd alternative

3rd alternative

4th alternative

Local operator(1st choice)

Figure 10.2: Centralised operator.

CAS and CCS Channel Associated Signalling, CAS and Common Channel Signalling, CCS are the two main principles used for signalling in telephony networks. They can be seen as the old (CAS) and the new (CCS) way of signalling, both in the sense that CCS protocols have a more comprehensive list of functionality’s but also in the fact that CAS tends to be analogue and CCS digital.

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CAS - Channel Associated Signalling The characteristics for CAS is that speech and signals travel the same way through the net. Some variations to this rule may occur:

� Signalling is done on the same channel as the speech (e.g. DC-signalling, in-band)

� The signalling is done on the speech channel, but in a different frequency range (out-band)

� Signalling is digital and carried out in time slot 16 (PCM signalling)

The way the signals are transferred varies, depending on the circuit and the transfer media. We will only mention three different ways.

� DC signalling: Signals are transferred in pulse form by means of changes in polarity and resistance of the connecting wires.

� Tone frequency signalling: Tones of constant frequencies carry the information. Distinction is made, depending on the frequency bands, between:

� in-band signalling, the signals lie within the 300-3400 Hz band.

� out-band signalling, where the signalling uses higher frequencies than the speech band.

� Digital signalling: On PCM connections, everything is ones and zeroes, no matter what is being transmitted.

Channel associated signalling between exchanges is usually divided into line and register signalling. Line signals are used for seizure, answer and clearing. They are used for monitoring of the line before, during and after the call set-up. Register signals are used to transmit the called number.

Line signalling Register signalling

Information Qty Small Large

Transfer rate (required)

Low High

Signalling period Long Short

Used during The whole call Call setup

Number of units (equipment)

Large Small

Line signals are needed during the whole call while register signals are used only during 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.

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CCS - Common Channel Signalling In CCS the signals travel their own way through the net, independent of which way the speech goes. The bearer of the signals can be seen as a network in itself, separate from the network that transfers the speech.

In CCS we no longer need to worry about the more or less sharp distinctions between register and line signals that we had in CAS.

SIGNALLING NETWORK

Figure 10.3: Signalling network.

Because the total time for signalling is very short, compared with the average call time, we can let a single, common signalling channel take care of all signalling for thousands of calls. This means that all traffic can share a common signalling device.

DPNSS - Digital Private Network Signalling System DPNSS is a signalling system for signalling between exchanges in a private network. Common channel signalling is used.

It is a quite old digital signalling system, first developed in Great Britain for the national telephone network. It was further developed later for use in international networks.

Since DPNSS uses CCS, the signalling is separated from the speech transmission. All signalling is transferred in timeslot 16.

A special kind of DPNSS, called Analogue DPNSS or APNSS, exists. It is used when facilities via the network are needed but where traffic between two exchanges is so low that subscription of a 2048 kbit/s digital interface is not economically motivated, or where only an analogue network is available. Thus the same facilities can be offered irrespectively of whether the network is digital or analogue.

In APNSS the speech and signalling are also physically separated. All signalling, such as connections, disconnection’s and digit transmission, will take place via modems instead of in time slot 16 in the digital connection. An

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interface board with V.24 interface has been developed for connection to modems.

Signalling

Speech

Modems

Figure 10.4: APNSS.

Speech transmission will take place via separate wire pairs on conventional analogue tie lines. These tie lines are not used for any signalling, only speech travels on them.

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ISDN - Integrated Services Digital Network ISDN may be seen as a logical progression of the digitisation of the telephone network and the development of digital data networks. It originated from a vision of development towards one network that was able to handle several different types of communication services; for example speech, data, text and pictures.

Analoguetelephonenetwork

IDN fordatacommunication

ISDN

IDN = IntegratedDigital Network

IDN fortelecommunication

Figure 10.5: Evolution towards ISDN.

Data networks and digital telephone networks are known as Integrated Digital Networks, IDN. Integrated, in this context, stands for integrated switching and transmission.

The network carries the digital channels all the way to the user. The interface to the user provides multiple services and allows any type of terminal to be connected to the network.

Different types of channels exists, with different transfer speeds. Common channels are the B-channel (64 kbit/s) and the D-channel (16/64 kbit/s). The B-channel is used for data communication and 64 kbit/s coded telephony. The D-channel is intended primarily for signalling. When it is not used for signalling, it can be used for data traffic.

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TE Terminal, e.g. telephone or terminal for teletex.- TE1: Terminal type 1. A terminal provided with an ISDN interface.- TE2: Terminal type 2. Non-ISDN terminal.

TA Terminal adapter. Connects terminals of type 2 tothe ISDN interface.

NT Network termination. Forms a physical and electricaltermination of the subscriber line.

TE1

TE2 TA

NT2(PBX)

R

SNT1

U ISDNnetwork

T

NT

PBX

Q

Figure 10.6: ISDN user configuration.

R, S, T, U and Q are reference points in the network where different interfaces are specified.

R - The reference point for connection of a TA for non-ISDN terminals to the ISDN.

S - The subscriber reference point for a Basic Rate Access (2B+D) to the ISDN.

T - Reference point for the connection of a Primary Rate Access (30B+D).

U - The reference point for connection between the ISDN exchange and a NT.

Q - The inter-PBX reference point to which a PBX is logically connected.

The NT is the system block that is used for connection to the ISDN.

In figure 6, a PBX acts as an interface between the NT and the ISDN exchange. Because the PBX can hold some of the functions of the NT, the NT is split into two parts, NT1 and NT2 (the PBX).

The MD110 is an ISDN PBX that can handle the functions of both NT1 and NT2. It is then called NT12. It provides its extensions users access to the ISDN.

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Definitions and concepts To better understand the initiation and the parameters needed to be able to communicate in a correct way some basic concepts should be understood.

Numbering plan When a system is added with channels of communication to external systems the numbering for the exchange becomes much more complicated than in a stand-alone system. It is quite easy to establish a private network where a users directory number not only depends on own exchange but also from where and who is calling him, such a situation would only result in confusion for the users.

Open numbering plan

850 864864-5444

Internal call5444

Call from other part of network

Figure 10.7: Open numbering plan.

An open numbering plan is where each location (exchange) in the private network needs an unique identifier, a location code, since different exchanges in the network can have extensions with identical directory numbers. The location code is necessary in order to be able to distinguish two extensions with identical directory numbers but in different exchanges. There is also a number type EN (own exchange number) that can be used to set the exchanges own location code.

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Closed numbering plan

4xxx 5xxx5444

Internal call5444

Call from other part of network

Figure 10.8: Closed numbering plan.

A closed numbering plan is used in a private network where there is no conflict between the first 1,2 or 3 digits in the directory number series. This means that it is not necessary to use a unique identifier as for an open numbering plan. Any number in the network is reached by dialling the directory number of the extension, irrespectively of in which exchange the calling party is situated.

Mixed numbering plan

A mixed numbering plan is used in a private network where the exchanges can be organised into groups. In each group we have a closed numbering plan and between the groups we have an open numbering plan.

Routes, trunks, lines and directions Traffic between an MD110 PBX and a public exchange/interworking exchange requires a line. This line is "initiated" (assigned) to a free equipment position in the system. A number of lines with the same characteristics together form a route. A number of routes (maximum 4), with the same or different characteristics, leading to the same external destination may be used to form a direction. The number of directions can be 100. A trunk individual is an individual on one of the external lines.

Routes can be initiated with different categories, such as signalling, service and traffic characteristics, to suit different types of external lines. Any route also goes either to a public or a private exchange. Another name for a Private route is Tie-line.

To each route (or direction) that permits outgoing traffic one or more external destinations shall be affiliated. It is possible to initiate up to seven alternative route choices to one external destination.

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PSTN

PABX

PABX

PSTN

ROU=1ROU=2

ROU=3

A-party

B-party

Figure 10.9: Alternative routes.

A day service and/or a night service position can be initiated (RODNI) to each incoming route or line, i.e. a common answering position for the route or individual for the line during day service and night service, respectively. An answering position for vacant numbers, to be used at incoming calls to vacant numbers, can also be initiated for each route. Furthermore, it is possible to assign each customer their own day and night switching positions (ROCNI, customer-dependent rerouting positions).

PSTN

Routes

Figure 10.10: Connection to the PSTN.

There are many types of routes, each serving a different purpose.

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Connection to the PSTN can be through:

� Direct In Dial, DID - 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.

� Integrated Services Digital Network, ISDN - A fully digital network, providing end-to-end digital transmission from the originator to the final destination. The network supplies both voice and data applications.

� Ring In/Loop out - Used for testing a single LIM system. Loops the signals directly back to the LIM.

Definitions

PTS Proceed To Send

Sometimes it is necessary for an exchange to stop and wait while then next exchange tries to digest the given information, when ready the other exchange will say go on again i.e. send PTS backward. With the command NAPTS one can tell the own exchange when to wait for PTS.

EOS End Of Selection

When one exchange have found a complete directory number it will tell the previous exchange that a B-part has been found, no more number information has to be send. By using the command NANLS we can explain to own exchange when to expect EOS from the other exchange, this has the advantage of releasing common resources and making the actual speech connection faster.

TCD Trunk Call Discrimination

It is possible to discriminate between users of the trunk lines i.e. only certain persons in the organisation are allowed to use some destinations in the network. It is also possible to distinguish between day and night usage, e.g. a guest telephone is during day time open for external traffic but only internal in night-time. This is done with the command NACDS. Note! This information is for the exchange with the A-part, if discrimination should take place in the network use FRL/TCM instead.

FRL/TCM Facilities Restriction Level Travelling Class Mark

For an incoming call to the exchange we have the opportunity to restrict its usage of internal function and/or transit to another exchange. For every trunk (and telephone) we have a FRL or TCM value, to connect two services the FRL for incoming value has to be equal or larger than the requested service. FRL is the default value if TCM is not sent on the network. The values are set on the trunk in parameter SEL (D10D12) and in ROC for the telephones.

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PCM-line For digital trunk lines the most common form of cabling is through a PCM-line. There is one definition for Europe (30B+D, 2Mbit) and one for USA (23B+D, 1.5Mbit). In Europe there are 32 time slots available on the line (numbered 0-31), where 0 is the synchronisation channel for the line and 16 is used by the (CCS-)protocol to send signalling information between the exchanges.

Initiation of routes Although there are a large number of commands to be used when setting up network connections, the concentration will be on the following commands:

ROCAI Sets up internal characteristics for the route, e.g. traffic direction, services available,bearer capabilities.

RODAI Describes the protocol that will be used in this route.

ROEQI Initiates individuals in the exchange that are to be connected to a route, called trunk lines.

RODDI Connects a route with a number that the subscriber will dial to reach the external line (the destination code).

Dest. codeRoute

Internalcharacteristics

RODDIDest. code

ROCAIInc./Outg./BothwaySignalling char.ServicesBearer capabilities

RODAIType of signallingVariations on traffic

ROEQITrunksEqu. pos.

MD110

4 1 2 3

TL-block

Figure 10.11: Actions of the RO commands.

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The ROCAI (Route Category Initiate) command The first thing to do is to initiate a route with the command ROCAI. A maximum of 32 routes per LIM or 99 routes per system can be stated.

ROU = Route numberSEL = Selection categorySIG = Signalling categoryTRAF = Traffic categoryTRM = Transmission characteristicsSERV = Service characteristicsDIST = Disturbance timeDISL = Disturbance levelNODG = Market dependent parameterBCAP = Bearer capabilities

ROCAI:ROU=...,SEL=,SIG=,TRAF=,TRM=,SERV=[,DIST=][,DISL=][,NODG=] [,BCAP=];

Figure 10.12: Command ROCAI.

ROU This parameter states the route number.

SEL States traffic routing characteristics such as:

� Criteria’s for rerouting at DID traffic.

� If malicious call tracing is allowed.

� Traffic direction, i.e. whether the route is open for incoming and /or outgoing traffic.

� Line selection at outgoing traffic.

SIG Sets the signaling characteristics between a route in the exchange and a public/interworking exchange. The following are of interest:

� Whether dial tone after seizure of the external line is to be generated in own or in cooperating exchange at outgoing call.

� Whether the route has a clear signal. Used to check if the parties 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 an operator.

� When the switch shall be through-connected.

� Type of signaling system, i.e. DPNSS, ISDN, MFC or decadic pulsing/DTMF.

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

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TRAF States the route traffic category.

This could be a traffic connection class that states which A-parties and B-parties that may be interconnected with the lines in the route.

TRM Selects the transmission characteristics in the switch, namely amplification or attenuation.

SERV Sets the route service category. The following are of interest:

� Whether the route is public or private. Used to provide correct ringing signal and display message at the called party.

� Whether call-back may be initiated to lines in the route.

DIST Sets the disturbance time for the route. Calls with duration times shorter than the stated disturbance time will be regarded as a disturbance.

DISL The parameter states the number of consecutive, faulty seizures on one external line that is tolerated before the external line is given a disturbance marking.

NODG This is a market-dependent parameter.

BCAP Sets the bearer capabilities of the route (outgoing side for ISDN). Possible values are:

� 64 kbit/s restricted/unrestricted

� 3.1 kHz audio

� Speech

� 7 kHz audio (used for video telephony and high-quality ISDN telephony)

� 16 kbit/s unrestricted digital

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The RODAI (Route Data Initiate) command This command is used to define the characteristics used by the interface between the external line and the system. The route must have been initiated with ROCAI. It is necessary to key command RODAI before the route is completely initiated.

ROU = Route numberTYPE = Type of signalling, TL-block in the MD110VARI = Variations on incoming trafficVARO = Variations on outgoing trafficVARC = Variations common for incoming and outgoing trafficFILTER = If filter equipment is used

RODAI:ROU=,TYPE= ,VARO= [,VARC=][,FILTER=]; ,VARI=

,VARI=,VARO=

Figure 10.13: Command RODAI.

TYPE States what type of signaling diagram, i.e. the TL function block in the MD110, that is used.

VARI VARO VARC

States the signal diagram variations for incoming or outgoing traffic (VARI/VARO) or variations common for incoming and outgoing traffic (VARC). Typical characteristics are:

� Type of register signaling.

� Whether end of selection (EOS) shall be sent.

� Whether B-answer shall be sent/received.

� Characteristics for different time supervisions.

FILTER States whether filter equipment is connected between tone sender and PABX.

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The ROEQI (Route Equipment Initiate) command The ROEQI command is used to initiate one or more equipment position(s) as external line(s) of a previously initiated route.

One or more lines can be initiated at the same time in a LIM. The line that comes first is associated with the equipment position stated. The rest of the external lines are associated with the subsequent free equipment positions of the right type in the same LIM.

ROU = Route numberTRU = Trunk line numberEQU = Equipment positionSQU = Signalling equipment positionINDDAT = Individual trunkdata

ROEQI:ROU=,TRU=... ,EQU=[,SQU=][,INDDAT=];

Figure 10.14: Command ROEQI.

ROU States to which route the new trunk line is connected to.

TRU States the trunk line number. LIM and serial number for the external line.

EQU States the equipment position for connection of the external line.

SQU States the equipment position for a signaling unit.

INDDAT Sets individual trunk data for the external line.

The RODDI (Route External Destination Data Initiate) command The command RODDI is used to initiate the ordinary route (or direction) choice, or an alternative route choice to an external destination. The external destination may be a public exchange. Up to seven alternative route choices can be initiated in order to reach a external destination.

Parameters of special importance are CHO, SRT, TRC and PRE.

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DEST = Destination codeCUST = Customer numberCHO = ChoicePRE = Predigits, digits to add to start of numberDRN = DirectionROU = Route numberTRC = Number of digits to truncateSRT = Start position in called number for digit transmissionNUMACK = Numbers to acknowledgeADC = Additional category for external traffic

RODDI:DEST= ,CHO= [,PRE=] [,TRC=][,SRT=],CUST=

,CUST=,CHO=

,DRN=

,ROU=

[,NUMACK=][,ADC=];

Figure 10.15: Command RODDI.

DEST States the external destination. This is the route access code for calls to an external destination.

CUST States the customer number in the exchange.

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.

DRN States direction to the external destination.

TRC/ 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 an 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 This parameter states the start position in the called number (possibly modified using TRC and PRE) from which digits shall be sent to the cooperating 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 cooperating exchange, SRT is set to 3. If the parameter is omitted, the digit sending will start with the first digit.

NUMACK States the number of digits from the interworking or public exchange to be acknowledged during predigit transmission.

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ADC Additional category for external traffic. Values in this parameter determine the type of number for private and public calling number. These values control what exchange numbers to use when composing the complete calling number.

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. Up to seven different options are possible.

Please note that the SERV and ADC parameters must be set properly to allow alternative routing.

The following picture shows an example with 4 different ways through to the B-part in the call.

Originator Public Network

Terminator

2nd

2nd

1st 3rd

3rd

4th

4th

Figure 10.16: Alternative routing.

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. This might be necessary to be able to go through the public network in the picture above.

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Example of a Direct In Dial route Use DynaText to find out more about what the specified parameters do. First, set the route category.

� ROCAI:

ROU= 4, SEL= 710000000000, TRM= 4, SERV= 3100000000, DIST= 005, DISL= 050, TRAF= 00151515, SIG= 010010000000;

Next, set up the route data.

� RODAI:

ROU= 4, TYPE= TL12, VARI= 00000000;

The last step is to connect the route to a physical equipment position.

� ROEQI:

ROU= 4, TRU= 1-1&&1-4, EQU= 1-0-62-1;

Initiation of an ISDN route Here is an example that sets up an ISDN route between two exchanges, A and B, with destination number 01 and 02 respectively.

Exchange ADestination code: 01

Exchange BDestination code:02

Figure 10.17: Example setup.

An explanation of the parameter values is given last in this chapter.

Parameters for exchange A

The first step is to set up the number series. We need to know the number to our own exchange and to the cooperating exchange.

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� NANSI: NUMTYP=EN, NUMSE=01;

� NANSI: NUMTYP=ED, NUMSE=02;

The next step sets up route number three from exchange A to exchange B.

� ROCAI:

ROU= 3, SEL= 711000000000, SIG= 011100000031, TRAF= 03151515, SERV= 3110000000, TRM= 4, BCAP= 101110;

� RODAI:

ROU= 3, TYPE= SL60, VARI= 15400000, VARO= 06800000, VARC= 00000310;

� RODDI:

DEST= 02, ROU= 3, SRT= 1, ADC= 0606100000000250;

� ROEQI:

ROU= 3, TRU= 1-1&&1-15, EQU= 1-0-10-1;

Parameters for exchange B

� NANSI:NUMTYP=EN,NUMSE=02;

� NANSI:NUMTYP=ED,NUMSE=01;

The route from exchange B to exchange A, route number four, is initiated in the same way as route 3 from A to B, with a few exceptions.

� ROCAI:

ROU= 4, SEL= 711000000000, SIG= 011100000031, TRAF= 03151515, SERV= 3110000000, TRM= 4, BCAP= 101110;

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� RODAI:

ROU= 4, TYPE= SL60, VARI= 15400000, VARO= 06B00000, VARC= 00000310;

� RODDI:

DEST= 01, ROU= 4, SRT= 1, ADC= 0606100000000250;

� ROEQI:

ROU= 4, TRU= 1-1&&1-15, EQU= 1-0-10-1;

Network synchronisation

When communicating it is not enough to be in the right place, being on time is also absolutely necessary. The term for this is synchronisation. This is done by deciding that one is master (sending clock) and the other is a slave (receives clock). If the line is to a public exchange the public net is always the master and the private machine has to follow the public one. The SCEXI command is used to establish synchronisation. In the slave PABXs the parameter FEML (First External Master Line) is used to define the equipment position in the LIM which contains the trunk board which is receiving synchronisation. FEML must always be against individual 0, the synchronisation channel (e.g. FEML =1-0-70-0).

PSTN

Synchronizationinformation

Figure 10.18: Synchronisation from PSTN.

In the picture above, a small network receives synchronisation from the public network. The lower two nodes get their synchronisation from the node connected to the PSTN.

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Explanation of the parameters

Here is a brief description of the values chosen for ISDN. For more information about the possible choices, consult DynaText.

Parameter SEL

7 Rerouting characteristics at DID. Rerouting at no answer, busy and any congestion.

1 Open for incoming traffic

1 Open for outgoing traffic.

0 Normal route.

0 Alternative route selection permitted.

00 Customer number, here not used.

0 Support virtual calls.

0 No malicious call tracing.

0 Default facility restriction level (FRL) category.

0 Default call service information (CSI) category.

0 Traveling class mark (TCM) not used.

Parameter SIG

0 Dial tone after line seizure not used.

1 Clear signal exists at incoming calls.

1 Clear signal exists at outgoing calls.

1 Answer signal (B-answer) at outgoing calls.

0 Not used.

0 Operator extend is not allowed when no clear signal exists.

0 A-party receives ring tone from cooperating exchange.

0 Switch through-connection in transit exchange, here after minimum number length.

0 Alternative routing is controlled by the first transit exchange.

0 Through connection for digit transmission in transit exchange takes place after seizure.

3 Signaling system is ISDN.

1 Net facilities are allowed.

Parameter TRAF

03 Class for abbreviated dialing.

15 TCD category incoming call at night.

15 TCD category incoming call at day.

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15 TCD category outgoing route.

Parameter SERV

3 Permitted to transmit call waiting tone on direct indialling to busy party. Reception of call waiting tone and intrusion.

1 Automatic call back allowed.

1 Tie line route.

0 No call metering.

0 Paging not allowed.

0 Least cost routing class of service (LCR COS). Search for route choice until threshold level 1. No queuing.

0 Release link trunk for operator (RLT) not used.

0 Presentation of calling number in ISDN/DPNSS networks is controlled by the extensions.

0 No request of calling number (A-number) from PSTN. (only relevant in some unique public trunks)

0 Number conversion, bearer capability substitution and high level compatibility not supported.

Parameter TRM

4 Row or column in the transmission matrix.

Parameter BCAP

101110 Bearer capability allowed: 64 kbit/s, 3.1 kHz audio, speech, 7 kHz audio.

Parameter TYPE

SL60 Type of signalling system is ISDN.

Parameter VARI

1 Support of generic functional protocol (GFP).

5 Support of UUS (User to User Signalling) service 1 and 2.

4 Support of UUS service 3.

00000 Not used.

NETWORKING


Parameter VARO

0 No UI-frame (User Information) support. ECMA protocol used (tie line).

6 No blocking at slip alarm. Include connected number in CONNECT message. User-User information element allowed in ALERTING message. Semipermanent connection not allowed.

* (See below) This position is set differently in exchange A and B.

0 Type of line is tieline.

00 Default TEI (Terminal End-point Identifier) value.

0 No call metering.

0 Not used.

*)

8

Fix connection between B-channel and external line. No channel negotiation is allowed. Priority for layer 1 is master. Layer 2 priority is NT2. No layer 3 priority.

B

Fix connection between B-channel and external line. No channel negotiation is allowed. Priority for layer 1 is master. Layer 2 priority is NT1. Layer 3 priority (network).

Parameter VARC

0000 Not used.

0 No support of progress message.

3 Ring signal is sent to cooperating exchange. Overlap receiving is allowed. No external line without signaling (only used with semipermanent connections). No reanswer.

1 Full ISDN functionality and no UUI (User-User Information) element limitation.

0 Type of signalling is ISDN. Hardware is 30B+D (TLU76/1).

Parameter ADC

0 Immediate seizure of line at dialing.

6 Type of called number is local private (B-number).

0 Type of calling public number is default.

6 Type of calling private number is local private (A-number).

1 ISDN UUI is allowed.

0 Non fiber network.

0 First party release.

0 MFC signals not used.

0 No transit seizure.

NETWORKING


0 Off-Hook queuing is not used.

0 Expensive route warning tone (ERWT) not sent.

0 Least cost routing allowed.

0 Travelling class mark (TCM) not sent.

25 Maximum number of transit exchanges, default.

0 No PNR (Private Network Routing) number translation.

Questions Use the text in this chapter and DynaText to answer the following questions.

1. What is CAS and CCS?

2. Explain the feature alternative routing?

Exercises

Exercise 1 - Initiate an ISDN route There are a couple of things you will have to do before you enter the RO-commands:

� Check that you have the program units TLP60, SLP60, ADEP, NIH and PNR loaded in your exchange (CN-command). If not loaded in the system follow the descriptions in the maintenance chapter about adding program units.

� Initiate the proper device boards (TLU76/1 for BC9).

� Set up your numbers for number types ED and EN. Ask the teacher about the numbers to the different exchanges in the classroom.

Now you are ready to initiate the ISDN route according to the example shown previously in this chapter. Don’t forget to synchronise the communication channel between the two exchanges.

� If you have the time look at the commands: NUTRI and RONDI.

Exercise 2 - Set up a complete network In this exercise all groups have to cooperate. The task is to connect all the exchanges into a starshaped ISDN-network. One central node and the others connected to this central node as satellites.

Hints: make a common numbering plan before you begin, decide who’s A and B and how the net is to be synchronised.

When everything is ready, it should be possible to call any extension from any other extension in the network.

Documents

Chapter 10 - Networking ........................................................................................10-2