SIST ETS 300 976 E6:2003

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.LQDigital cellular telecommunications system (Phase 2+) (GSM); General requirements on interworking between the Public Land Mobile Network (PLMN) and the Integrated Services Digital Network (ISDN) or Public Switched Telephone Network (PSTN) (GSM 09.07 version 5.7.1)33.080Digitalno omrežje z integriranimi storitvami (ISDN)Integrated Services Digital Network (ISDN)33.070.50Globalni sistem za mobilno telekomunikacijo (GSM)Global System for Mobile Communication (GSM)33.040.35Telefonska omrežjaTelephone networksICS:Ta slovenski standard je istoveten z:ETS 300 976 Edition 6SIST ETS 300 976 E6:2003en01-december-2003SIST ETS 300 976 E6:2003SLOVENSKI
STANDARD
EUROPEANETS 300 976TELECOMMUNICATIONOctober 1998STANDARDSixth EditionSource: SMGReference: RE/SMG-040907QR7ICS:33.020Key words:Digital cellular telecommunications system, Global System for Mobile communications (GSM)GLOBAL SYSTEM
FOR MOBILE COMMUNICATIONSRDigital cellular telecommunications system (Phase 2+);General requirements on interworking between the Public LandMobile Network (PLMN) and the Integrated Services DigitalNetwork (ISDN) or Public Switched Telephone Network (PSTN)(GSM 09.07 version 5.7.1)ETSIEuropean Telecommunications Standards InstituteETSI SecretariatPostal address: F-06921 Sophia Antipolis CEDEX - FRANCEOffice address: 650 Route des Lucioles - Sophia Antipolis - Valbonne - FRANCEInternet: secretariat@etsi.fr - http://www.etsi.orgTel.: +33 4 92 94 42 00 - Fax: +33 4 93 65 47 16Copyright Notification: No part may be reproduced except as authorized by written permission. The copyright and theforegoing restriction extend to reproduction in all media.© European Telecommunications Standards Institute 1998. All rights reserved.SIST ETS 300 976 E6:2003

Page 2ETS 300 976 (GSM 09.07 version 5.7.1): October 1998Whilst every care has been taken in the preparation and publication of this document, errors in content,typographical or otherwise, may occur. If you have comments concerning its accuracy, please write to"ETSI Standards Making Support Dept." at the address shown on the title page.SIST ETS 300 976 E6:2003

Page 3ETS 300 976 (GSM 09.07 version 5.7.1): October 1998ContentsForeword.71Scope.92Normative references.93Definitions and abbreviations.114Introduction.135Not used.136Network Characteristics.146.1Key Characteristics of Networks Concerned.146.1.1Characteristics of PLMNs.146.1.2Characteristics of PSTNs.146.1.3Characteristics of ISDN.157Interworking classifications.157.1Service interworking.157.2Network interworking.157.3Signalling interworking.177.4Numbering.177.5Supplementary service interworking.178Compatibility and subscription checking.189Interworking to PSTN.189.1Speech Calls.189.1.1Interworking indications to PLMN terminal.189.1.2Transmission aspects.189.1.3Generation of In-band Tones and Announcements (PLMN-PSTN).189.2Data Calls.189.2.1Network interworking mobile originated.199.2.1.1Selection of interworking function.199.2.1.2Modem Selection.209.2.1.3DTE/Modem interface (Filtering).209.2.1.4Mapping of BC-IE from GSM 04.08 to ISUP (or other).219.2.2Network Interworking Mobile terminated PSTN Originated.219.2.3Transparent service support.269.2.3.1Not used.269.2.3.2Rate adaptation process in MSC/IWF.269.2.3.3Mapping of signalling MS/MSC/IWF to modem interfacerequirements.269.2.3.4Establishment of end-to-end terminal synchronizations.279.2.3.5Network Independent Clocking (NIC).289.2.4Non-transparent service support.299.2.4.1MSC-IWF Rate adaptation scheme.299.2.4.2Protocol layer structure in the MSC/IWF.299.2.4.3Re-constitution of user data.299.2.4.4Layer 2 relay functionality.299.2.4.5In band signalling mapping flow control.299.2.4.5.1Conditions requiring flow controltowards the fixed network.30SIST ETS 300 976 E6:2003

Page 4ETS 300 976 (GSM 09.07 version 5.7.1): October 19989.2.4.5.2Conditions requiring flow controltowards the MS.309.2.4.6Data buffers.309.2.4.6.1Transmit buffers (towards MS).309.2.4.6.2Receive buffers (from MS).309.2.4.7Transportation of the Break condition.309.2.4.8In band signalling mapping modem status information.319.2.4.9Support of out-band flow control.319.2.4.10Establishment of end-to-end terminal synchronizations.319.2.4.11Data compression.329.3Interworking Alternate Speech / Data Calls.329.3.1Alternate Speech/Data Interworking.329.3.1.1General.329.3.1.2Mobile originated PSTN terminated calls.329.3.1.3PSTN originated mobile terminated calls.329.3.2Speech followed by data interworking.339.3.2.1General.3310Interworking to the ISDN.3310.1Speech Calls.3410.2Data Calls.3410.2.1Network interworking mobile originated.3410.2.1.1Circuit switched calls.3410.2.1.2Packet calls.3410.2.2Network interworking mobile terminated.3410.2.2.1Circuit switched calls.5310.2.2.2Packet calls.5310.2.3Transparent service support (see GSM 03.10).5310.2.3.1MSC - IWF rate adaptation scheme.5310.2.3.2Rate adaptation process in MSC/IWF.5410.2.3.3Mapping of signalling MS/MSC/IWF to modem interfacerequirements.5410.2.3.4Establishment of end-to-end terminal synchronizations.5410.2.3.5Network independent Clocking (NIC).5510.2.4Non-transparent service support (See GSM 03.10).5510.2.4.1MSC - IWF Rate adaptation scheme.5510.2.4.2Protocol layer structure in the MSC/IWF.5510.2.4.3Re-constitution of user data.5610.2.4.4Layer 2 relay functionality.5610.2.4.5In band signalling mapping flow control.5610.2.4.5.1Conditions requiring flow control - ifflow control is provided -towards thefixed network.5710.2.4.5.2Conditions requiring flow controltowards the MS.5710.2.4.6Data buffers.5710.2.4.6.1Transmit buffers (towards MS).5710.2.4.6.2Receive buffers (from MS).5710.2.4.7BREAK Indication.5810.2.4.8Signalling mapping modem status information or in bandrate adapted frame information.5810.2.4.9 Support of out-band flow control.5810.2.4.10Synchronizations.5810.2.4.10.1V.110 and V.120 Framesynchronizations.5810.2.4.10.2RLP Frame start indication.5810.2.4.10.3L2R Frame synchronizations.5810.2.4.10.4Establishment of end-to-end terminalsynchronizations.5810.2.4.11Data compression.5910.2.4.12Additional aspects of V.120 Interworking.5910.2.4.12.1V.120 Signalling parameters.60SIST ETS 300 976 E6:2003

Page 5ETS 300 976 (GSM 09.07 version 5.7.1): October 199810.2.4.12.2V.120 Protocol parameters.6010.2.4.12.3Data compression on the ISDN.6010.2.4.13Interworking with restricted 64 kbit/s networks.6010.2.4.13.1Rate adaptation.6010.2.4.13.2MSC - ISDN signalling.6010.2.5DTE/Modem interface (Filtering).6010.3Interworking Alternate speech data calls.6210.3.1Alternate speech data bearer interworking.6210.3.1.1General.6210.3.1.2Mobile originated ISDN terminated.6210.3.1.3ISDN originated mobile terminated.6210.3.2Speech followed by data interworking.6310.3.2.1General.6311Frame Synchronization.6311.1Initial frame synchronization.6311.2Action on loss of frame synchronization for non transparent services.6311.3Action on loss of frame synchronization for transparent services.64Annex A (Informative):SDLs.65Annex B (Informative):Change history.67History.68SIST ETS 300 976 E6:2003

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Page 7ETS 300 976 (GSM 09.07 version 5.7.1): October 1998ForewordThis European Telecommunication Standard (ETS) has been produced by the Special Mobile Group(SMG) of the European Telecommunications Standards Institute (ETSI).This ETS identifies the Mobile-services Switching Centre/Interworking functions (MSC/IWFs) andrequirements to support interworking between:i)PLMN and PSTNii)PLMN and ISDNwithin the digital cellular telecommunications system.The contents of this ETS are subject to continuing work within SMG and may change following formalSMG approval. Should SMG modify the contents of this ETS, it will then be resubmitted for OAP by ETSIwith an identifying change of release date and an increase in version number as follows:Version 5.x.ywhere:ythe third digit is incremented when editorial only changes have been incorporated in thespecification;xthe second digit is incremented for all other types of changes, i.e. technical enhancements,corrections, updates, etc.Transposition datesDate of adoption of this ETS:23 October 1998Date of latest announcement of this ETS (doa):31 January 1999Date of latest publication of new National Standardor endorsement of this ETS (dop/e):31 July 1999Date of withdrawal of any conflicting National Standard (dow):31 July 1999SIST ETS 300 976 E6:2003

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Page 9ETS 300 976 (GSM 09.07 version 5.7.1): October 19981ScopeThis European Telecommunication Standard (ETS) identifies the Mobile-services SwitchingCentre/Interworking Functions (MSC/IWFs) and requirements to support interworking between:a)PLMN and PSTNb)PLMN and ISDNIt is not possible to treat ISDN and PSTN as one type of network, even when both ISDN and PSTNsubscribers are served by the same exchange because of the limitations of the PSTN subscribers accessi.e. analogue connection without D-channel signalling.Within this ETS, the requirements for voice and non-voice (data) calls are considered separately.2Normative referencesThis ETS incorporates by dated and undated reference, provisions from other publications. Thesenormative references are cited at the appropriate places in the text and the publications are listedhereafter. For dated references, subsequent amendments to or revisions of any of these publicationsapply to this ETS only when incorporated in it by amendment or revision. For undated references, thelatest edition of the publication referred to applies.[1]CCITT Recommendation G.711: "Pulse code modulation (PCM) of voicefrequencies".[2]CCITT Recommendation I.460: "Multiplexing, rate adaption and support ofexisting interfaces".[3]CCITT Recommendation V.25: "Automatic answering equipment and/or parallelautomatic calling equipment on the general switched telephone networkincluding procedures for disabling of echo control devices for both manually andautomatically established calls".[4]CCITT Recommendation V.42bis: "Data Compression for Data CircuitTerminating Equipment (DCE) using Error Correction Procedures"[5]CCITT Recommendation V.110: "Support of data terminal equipments (DTEs)with V-Series interfaces by an integrated services digital network".[6]ETS 300 102-1 Edition 1 (1990): "Integrated Services Digital Network (ISDN);User-network interface layer 3
Specifications for basic call control".[7]ETS 300 121: "Integrated Services Digital Network (ISDN); Application of theISDN User Part (ISUP) of CCITT Signalling System No.7 for international ISDNinterconnections (ISUP version 1)".[8]GSM 01.04 (ETR 350): "Digital cellular telecommunication system (Phase 2+);Abbreviations and acronyms".[9]GSM 02.01: "Digital cellular telecommunication system (Phase 2+); Principles oftelecommunication services supported by a GSM Public Land Mobile Network(PLMN)".[10]GSM 02.02 (ETS 300 904): "Digital cellular telecommunications system(Phase 2+); Bearer Services (BS) supported by a GSM Public Land MobileNetwork (PLMN)".[11]GSM 02.03 (ETS 300 905): "Digital cellular telecommunications system(Phase 2+); Teleservices supported by a GSM Public Land Mobile Network(PLMN)".SIST ETS 300 976 E6:2003

Page 10ETS 300 976 (GSM 09.07 version 5.7.1): October 1998[12]GSM 02.04 (ETS 300 918): "Digital cellular telecommunications system(Phase 2+); General on supplementary services".[13]GSM 02.81: "Digital cellular telecommunication system; Line identificationsupplementary services - Stage 1".[14]GSM 02.82: "Digital cellular telecommunication system; Call Forwarding (CF)supplementary services - Stage 1".[15]GSM 02.83: "Digital cellular telecommunication system; Call Waiting (CW) andCall Hold (HOLD) supplementary services - Stage 1".[16]GSM 02.84: "Digital cellular telecommunication system; MultiParty (MPTY)supplementary services - Stage 1".[17]GSM 02.85: "Digital cellular telecommunication system; Closed User Group(CUG) supplementary services - Stage 1".[18]GSM 02.86: "Digital cellular telecommunication system; Advice of charge (AoC)supplementary services - Stage 1".[19]GSM 02.88: "Digital cellular telecommunication system; Call Barring (CB)supplementary services - Stage 1".[20]GSM 03.03 (ETS 300 927): "Digital cellular telecommunications system(Phase 2+); Numbering, addressing and identification".[21]GSM 03.08: "Digital cellular telecommunication system (Phase 2+);Organization of subscriber data".[22]GSM 03.11 (ETS 300 928): "Digital cellular telecommunications system;Technical realization of supplementary services".[23]GSM 03.45 (ETS 300 931): "Digital cellular telecommunications system;Technical realization of facsimile group 3 transparent".[24]GSM 03.46: "Digital cellular telecommunication system; Technical realization offacsimile group 3 non-transparent".[25]GSM 03.50 (ETS 300 903): "Digital cellular telecommunications system(Phase 2+); Transmission planning aspects of the speech service in the GSMPublic Land Mobile Network (PLMN) system".[26]GSM 04.08 (ETS 300 940): "Digital cellular telecommunications system(Phase 2+); Mobile radio interface layer 3 specification".[27]GSM 04.21 (ETS 300 945): "Digital cellular telecommunications system; Rateadaption on the Mobile Station - Base Station System (MS - BSS) interface".[28]GSM 04.22 (ETS 300 946): "Digital cellular telecommunications system(Phase 2+); Radio Link Protocol (RLP) for data and telematic services on theMobile Station - Base Station System (MS - BSS) interface and the Base StationSystem - Mobile-services Switching Centre (BSS - MSC) interface".[29]GSM 07.01 (ETS 300 913): "Digital cellular telecommunications system(Phase 2+); General on Terminal Adaptation Functions (TAF) for MobileStations (MS)".[30]GSM 07.02 (ETS 300 914): "Digital cellular telecommunications system(Phase 2+); Terminal Adaptation Functions (TAF) for services usingasynchronous bearer capabilities".SIST ETS 300 976 E6:2003

Page 11ETS 300 976 (GSM 09.07 version 5.7.1): October 1998[31]GSM 07.03 (ETS 300 915): "Digital cellular telecommunications system(Phase 2+); Terminal Adaptation Functions (TAF) for services usingsynchronous bearer capabilities".[32]GSM 07.05: "Digital cellular telecommunication system (Phase 2+); Use of DataTerminal Equipment - Data Circuit terminating Equipment (DTE - DCE) interfacefor Short Message Service (SMS) and Cell Broadcast Service (CBS)".[35]GSM 08.20: "Digital cellular telecommunication system; Rate adaption on theBase Station System - Mobile-services Switching Centre (BSS - MSC)interface".[36]GSM 08.60 (ETS 300 737): "Digital cellular telecommunications system(Phase 2+); Inband control of remote transcoders and rate adaptors forEnhanced Full Rate (EFR) and full rate traffic channels".[37]GSM 09.02 (ETS 300 974): "Digital cellular telecommunications system(Phase 2+); Mobile Application Part (MAP) specification".[38]GSM 09.03: "Digital cellular telecommunication system; Signalling requirementson interworking between the Integrated Services Digital Network (ISDN) orPublic Switched Telephone Network (PSTN) and the Public Land MobileNetwork (PLMN)".[39]GSM 09.05: "Digital cellular telecommunication system; Interworking betweenthe Public Land Mobile Network (PLMN) and the Packet Switched Public DataNetwork (PSPDN) for Packet Assembly/Disassembly facility (PAD) access".[40]GSM 09.06 (ETS 300 975): "Digital cellular telecommunications system(Phase 2+); Interworking between a Public Land Mobile Network (PLMN) and aPacket Switched Public Data Network/Integrated Services Digital Network(PSPDN/ISDN) for the support of packet switched data transmission services".[41]CCITT Recommendation V.120: "Support by an ISDN of data terminalequipment with V-Series type interfaces with provision for statisticalmultiplexing".[42]ETR 018: "Integrated Services Digital Network (ISDN); Application of the BearerCapability (BC), High Layer Compatibility (HLC) and Low Layer Compatibility(LLC) information elements by terminals supporting ISDN services".[43]CCITT Recommendation I.464: "Multiplexing, rate adaption and support ofexisting interfaces for restricted 64 kbit/s transfer capability".[44]CCITT Recommendation Q.922 (1992): "DSS 1 Data link layer: ISDN data linklayer specification for frame mode bearer services"NOTE:As regards ETS 300 102-1 [6], the first edition of this ETS from 1990 shall be used,with one exception: the encoding of the field modem type in the ISDN BC-IE shall behandled as specified in table 6A and 6B of GSM 09.07.3Definitions and abbreviationsUse is made of the following terms within this ETS. These terms refer to information requirementsnecessary to support interworking functions, some of these terms will be identifiable with their use in otherGSM specifications.bearer capability information: Specific information defining the lower layer characteristics requiredwithin the network.low layer compatibility information: Information defining the lower layer characteristics of the terminal.SIST ETS 300 976 E6:2003

Page 12ETS 300 976 (GSM 09.07 version 5.7.1): October 1998high layer compatibility information: Information defining the higher layer characteristics of theterminal.compatibility information: This term subsumes the entirety of Bearer Capability, Low LayerCompatibility, High Layer Compatibility, Progress Indicator and Address Information conveyed out-of-bandprior to call establishment for the support of compatibility checking and terminal/function/service selectionat the ISDN-type user-network interface.protocol identifier: Information defining the specific protocols utilized for the support of data transfer by aterminal.progress indicator: Information supplied to indicate to the terminal that network interworking has takenplace.out-of-band parameter exchange: Information exchanged via an associated or non-associatedsignalling link e.g. SS No 7.PSTN: Subscriber to network interface supports only analogue terminals.ISDN: Subscriber to network interface supports digital or analogue terminals, plus a standardized user tonetwork associated signalling system and a standardized internetwork signalling system.autobauding type 1: This information element value may be contained in the setup or call confirmmessages from the MS in association with a non transparent data service. This implies that the MSC/IWFmay select any speed and modem type according to what it can negotiate with the remote modem on thePSTN/ISDN. The maximum speed to be used by the MSC/IWF is the user speed indicated in thesetup/call confirm message.multi self selecting speed modem: This term applies to V series modems capable of handling one ormore lower speeds as a fall back position. When such a modem is requested in the call setup or callconfirm message from the MS in association with a non transparent service, the MSC/IWF may select anyof the speeds supported according to the negotiation with the remote modem on the PSTN/ISDN. In thisinstance the maximum starting negotiation speed to be used by the MSC/IWF is the one indicated by theuser speed in the setup/call confirm message.unrestricted 64 kbit/s network: A digital network which has 64 kbit/s octet-structured InformationTransfer Capability (ITC) with no restrictions on the contents of each octet.restricted 64 kbit/s network: CCITT I.464 defines '"restricted 64 kbit/s transfer capability" as "64 kbit/soctet-structured capability with the exception that an all-zero octet is not permitted". In this specification,the term "restricted 64 kbit/s network" refers not only to networks with the I.464 restriction but also tothose in which the 8th bit of each octet is unusable for data transmission.directly connected restricted 64 kbit/s network: A restricted 64 kbit/s network which is connecteddirectly to the MSC/IWF.indirectly connected restricted 64 kbit/s network: A restricted 64 kbit/s network which is connected tothe MSC/IWF via an unrestricted 64 kbit/s network.In addition to the following, abbreviations used in this ETS are listed in GSM 01.04 [8].ADPCMAdaptive Differential Pulse Coded ModulationDPDial PulseDSS1Digital Subscriber Signalling 1ITCInformation Transfer CapabilityLELocal ExchangeNTNetwork TerminationPABXPrivate Automatic Branch ExchangeSPCStored Program ControlSS No.7Signalling System No.7TETerminal EquipmentSIST ETS 300 976 E6:2003

Page 13ETS 300 976 (GSM 09.07 version 5.7.1): October 1998TATerminal AdaptorTUPTelephone User Part (of Signalling System No.7)UNIUser Network Interface4IntroductionGeneral Network Interworking Scenarios are described in GSM 09.01. Since the numbering plan for theISDN era (E.164) includes the numbering plan for the telephone network (E.163), it is not possible todistinguish by the number whether a given subscriber is a PSTN or ISDN subscriber. Further, in somecountries both PSTN and ISDN subscribers will be connected to the same exchange, so the onlydifference for this type of combined network will be in the nature of the customer access. In this documenta PSTN is considered to support only an analogue interface towards the subscriber. An ISDN shall beconsidered to support digital interface towards the subscriber. In addition, the ISDN is considered tosupport a standardized outband signalling protocol both between the subscriber and the network andwithin the network, i.e DSS1 and ISUP, thus enabling the generation and transport of CompatibilityInformation for compatibility checking and terminal/function/service selection at the user-network interfaceas well as for MSC/IWF selection.There now exist networks which do not fall into either of these categories in that they provide for digitalconnectivity from subscriber to subscriber through the network. The subscribers have access to a widerange of services by a limited set of standard multi-purpose user network interfaces. However, thesenetworks do not support the standardized inter-exchange signalling protocol throughout, in that they aree.g. using TUP or National User Part (NUP). These types of network support 64 kbit/s connections, so inservice support are comparable to ISDN, however, the signalling system provided may not supporttransport of all Compatibility Information allowed for in the standardized ISDN signalling. This documentwill therefore identify interworking to PSTN and ISDN on the principle of the network characteristics asidentified in the previous paragraph. The aforementioned existing networks then constitute one particularcase in the ISDN interworking scenarios. These cases will be itemized when the implication of the variousdegrees of exhaustiveness of the Compatibility Information - delivered via the ISDN - used for deducting aGSM Basic Service needs to be set forth.When two dissimilar networks are required to interwork in order to support a communication between twosubscribers, one on each network, a number of Interworking Functions (MSC/IWFs) are required tosupport the communication. Some of these are related to the differences in signalling and are dealt with inGSM 09.03.Examples of other aspects of interworking are:a)the need or otherwise of echo control devices;b)the need or otherwise of modem pools and network-based rate adaptation.For the purposes of determining the required MSC/IWFs, it is necessary, however, to consider separatelyeach type of interworking (i.e. PLMN-ISDN and PLMN-PSTN) since, in the worst case, "PSTN" could referto an essentially analogue network with electromechanical switching not controlled by software andwithout common-channel signalling.Some facilities associated with alternate speech and data may not be available with version 1 of the MAP(GSM 09.02). Version 1 of the Mobile Application Part (MAP) does not support transfer between the HLRand VLR, and VLR and VMSC of multiple bearer capabilities. In addition, version 1 of the MAP does notsupport in-call modification and channel mode modification following an inter-MSC handover.5Not usedSIST ETS 300 976 E6:2003

Page 14ETS 300 976 (GSM 09.07 version 5.7.1): October 19986Network Characteristics6.1Key Characteristics of Networks ConcernedTable 1/09.07: Key Characteristics of Networks ConcernedCharacteristicGSM PLMNISDNPSTNSubscriber InterfaceDigitalDigitalAnalogueUser-network signallingGSM 04.08DSS1, other UNIsloop-disconnect and DTMFUser-terminal equipmentsupportedMT0, MT1 or MT2functions (seeGSM 04.02)Digital TE(ISDN NT, TE1 orTE2+TA)see e.g. I.411Analogue TE (e.g. dial pulsetelephones PABXs modemequipped DTEs)Inter-exchange signallingSS No.7 ISUP TUP+,MAPSS No.7 ISUPTUP+, TUP, NUPChannel associated(e.g. R2, No.4, No.5) orcommon channel (e.g.No.6)Transmission facilitiesDigitalDigitalAnalogueExchange typesDigitalDigitalAnalogue/digitalInformation transfer modeCircuitCircuit/PacketCircuitInformation transfer capabilitySpeech, digitalunrestricted, alternatespeech/ group 3 fax etc.Speech, digitalunrestricted,3,1 kHz audio,video etc.3,1 kHz audio(voice/voice- band data)6.1.1Characteristics of PLMNsThe GSM PLMN is fully defined in the GSM Technical Specifications.6.1.2Characteristics of PSTNsBecause of the efforts at an early stage to standardize ISDNs in different countries, the differencesbetween any two ISDNs will be small compared with the differences between PSTNs, which have evolvedin different ways in different countries. In some cases the evolution has occurred over many decades, andtherefore each PSTN is distinct, and for a recommendation on interworking, it is necessary to makecertain assumptions about a generalized PSTN.Whilst the key characteristics of PSTNs are given in table 1/09.07 above, the specific MSC/IWFs neededto allow interworking between a PLMN and a PSTN will depend on the nature of the PSTN concerned.Table 2/09.07 below gives a number of categories that can be used to classify PSTNs and a number ofpossibilities within each category.SIST ETS 300 976 E6:2003

Page 15ETS 300 976 (GSM 09.07 version 5.7.1): October 1998Table 2/09.07: Characteristics of PSTNsCategoryPossibilities within CategoryType of subscribera) PSTN with loop disconnect subscriber signalling (10 pps)signallingb) PSTN with DTMF subscriber signallingType of interexchangea) PSTN with channel-associated signallingsignallingb) PSTN with common-channel signallingType of interexchangea) Analoguetransmissionb) DigitalType of exchangea) PSTN with electro-mechanical switchingswitchingb) PSTN with electronic (non-digital) switchingc) PSTN with electronic digital switchingType of exchangea) Non-SPCcontrolb) SPCNOTE:Under each category, it is possible that a PSTN will have a combination of thepossibilities rather than only one.6.1.3Characteristics of ISDNFor the "standardized ISDN" in principle taken into account here, these are defined in the ETS-series.7Interworking classifications7.1Service interworkingService interworking is required when the Teleservices at the calling and called terminals are different. Noservice interworking, except for facsimile group 3 (GSM Teleservice 61 or 62 interworking with standardfacsimile group 3 service), has been identified as a requirement of the GSM system for PSTN/ISDNnetwork based services.7.2Network interworkingNetwork interworking is required whenever a PLMN and a non-PLMN together are involved to provide anend to end connection and may be required in instances of PLMN to PLMN connections.The concept of Bearer Services was developed for the ISDN and has been extended to the PLMN. Abearer service is defined (in GSM 02.01) as:A type of telecommunication service that provides the capability for the transmission of signals betweenuser-network interfaces.Bearer services are described by a number of attributes, where an attribute is defined as a specifiedcharacteristic of an object or element whose values distinguish that object or element from others.For the purpose of this TS, a PSTN is assumed to provide a bearer service which equates to an ISDN3,1 kHz audio bearer service.Refer to GSM 02.02 for complete list of bearer services. Refer to GSM 04.08 for coding of BearerCapabilities.SIST ETS 300 976 E6:2003

Page 16ETS 300 976 (GSM 09.07 version 5.7.1): October 1998Table 3/09.07: Bearer Service InterworkingBearer service category inGSM PLMNBearer Service in GSMBearer service inISDNService inPSTNCircuit mode unstructured withunrestricted digital capabilityAsynchronous Data 300 bit/sAsynchronous Data 1.2 kbit/sTransparent andNon transparentAsynchronous Data1 200/75 bit/sNotApplicableAsynchronous Data 2.4 kbit/sCct modestructured 64 kbit/sunrestrictedAsynchronous Data 4.8 kbit/sAsynchronous Data 9.6 kbit/sAsynchronous Data generalCircuit mode unstructured withunrestricted digital capabilityTransparentSynchronous Data 1.2 kbit/sSynchronous Data 2.4 kbit/sSynchronous Data 4.8 kbit/sSynchronous Data 9.6 kbit/sSynchronous Data generalCircuit mode unstructured withunrestricted digital capability.Non-transparentPacket Servicessee GSM 09.06Packet Servicessee GSM 09.063,1 kHz Audio Ex PLMNTransparent andNon-transparentAsynchronous Data 300 bit/sAsynchronous Data 1.2 kbit/sCct Mode3,1 kHzAudioAsynchronous Data1 200/75 bit/sCct Mode3,1 kHz AudioAsynchronous Data 2.4 kbit/sAsynchronous Data 4.8 kbit/sAsynchronous Data 9,6 kbit/sAsynchronous Data general3,1 kHz Audio Ex PLMNSynchronous Data 1.2 kbit/sTransparentSynchronous Data 2.4 kbit/sSynchronous Data 4.8 kbit/sSynchronous Data 9.6 kbit/sSynchronous Data general(continued)SIST ETS 300 976 E6:2003

Page 17ETS 300 976 (GSM 09.07 version 5.7.1): October 1998Table 3/09.07 (concluded): Bearer Service InterworkingBearer service category inGSM PLMNBearer Service in GSMBearer service inISDNService inPSTN3,1 kHz Audio Ex PLMNNon TransparentSee GSM 09.06See GSM 09.06Alternate speech /data circuitmode unstructured with 3,1 kHzaudio ex PLMNTransparentalternate speech/asynchronous(with user rates 300 to28800 bit/s as above)alternate speech/synchronous(with user rates 1200 to28800 bit/s as above)Alternate speech/data circuitmode unstructured with 3,1 kHzaudio ex PLMNnon transparentalternate speech/asynchronous(with user rates 300 to28800 bit/s as above)Cct mode3,1 kHz AudioCct mode3,1 kHzAudioCircuit mode with speechfollowedby dataTransparent and NontransparentCct mode speech followed bydata300 to 28800 bit/sasynchronous as aboveCct mode3,1 kHz audioTable 4/09.07: Network interworking of GSM TeleservicesTeleservice inGSM PLMNLower layer capabilitiesaddressed in the GSM BearerCapabilities IEBearer servicein ISDNServicein PSTNTelephonyUnstructured with speech capabilitySpeech or Cct modeCct ModeEmergency callsUnstructured with speech capability3,1 kHz audio3,1 kHz audioAlternate speech/facsimile group 3Data Cct duplex synchronousaccessalternate speechgroup 3 faxCct mode 3,1 kHzaudioCct mode 3,1 kHzaudioAutomaticFacsimile group 3Data Cct duplex synchronousaccessgroup 3 faxCct mode 3,1 kHzaudioThis table does not identify any relationship between Teleservices in the GSM PLMN with those in theISDN/PSTN, it is merely to identify the interworking of the lower network layers of that teleservice with thenetwork layers i.e. bearer service in the ISDN/PSTN.7.3Signalling interworkingSee GSM 09.03.7.4NumberingSee GSM 03.03.7.5Supplementary service interworkingFor general aspects of supplementary services refer to GSM 03.11, GSM 03.8x and 03.9x series.SIST ETS 300 976 E6:2003

Page 18ETS 300 976 (GSM 09.07 version 5.7.1): October 1998Not every supplementary service may be used in combination with each basic service. The applicability ofeach supplementary service for a basic service is defined in GSM 02.8x and 02.9x-series. Certainapplication rules are also set out in GSM 02.03, 09.05 and 09.06.This subclause only deals with data service specific aspects of supplementary services, i.e. MSC/IWFfunctions concerned in combination with supplementary services. This interworking is described inGSM 02.04, GSM 02.8x, and 02.9x-series, GSM 03.11, GSM 03.8x and GSM 03.9x-series, if applicable.8Compatibility and subscription checkingCompatibility checking is carried out on the following items:a)Low layer compatibility - utilizing low layer compatibility and bearer capability information elements.b)High layer compatibility - utilizing high layer compatibility information element.The use of the progress indicator for compatibility checking is outside the scope of this ETS.Indication of compatibility requirements is carried out as described in subclause 9.2.2 under "a) Functionaloperation" or "b) Mobile subscriber indicates requirement in call confirmation message" and subclause10.2.2 "Network interworking mobile terminated".For subscription checking, relevant for the interworking described in clauses 9 and 10 of this ETS, refer toGSM 02.01.9Interworking to PSTN9.1Speech Calls9.1.1Interworking indications to PLMN terminalAn indication to inform the PLMN terminal that:i)instead of receiving out-of-band indications for certain types of failure conditions, a tone orannouncement will be received in-band from the PSTN.ii)the available compatibility information will be not exhaustive for deducing a GSM Basic Service andthere will be a limitation on address - the terminal may be required to accept the call on the basis ofindicating its compatibility requirements.iii)(if a DTE) in-band handshaking signals should be anticipated.9.1.2Transmission aspectsIncludes control of Speech Processing and Echo Control Devices, see GSM 03.50.9.1.3Generation of In-band Tones and Announcements (PLMN-PSTN)In-band tones and announcements shall be provided for all speech and 3,1 kHz audio bearer servicesbetween a PLMN and a PSTN.9.2Data CallsLow Layer Compatibility Checking on the received GSM bearer capability information element will becarried out by the MSC/IWF to check if the call setup is compatible to the bearer service (3,1 kHz audio)provided by a PSTN and to the IWFs provided by the PLMN.In case the call setup does not conform to these requirements (e.g. an information transfer capabilityvalue "unrestricted digital information" is requested), the call shall fail with an error cause indicating thatthe network is unable to support the service requested.SIST ETS 300 976 E6:2003

Page 19ETS 300 976 (GSM 09.07 version 5.7.1): October 1998As well as compatibility checking subscription checking shall be performed. If the subscription check failsthe call setup shall be rejected.For the case where the MS offers negotiable values in the GSM bearer capability information element(e.g. both transparent and non-transparent connection element) refer to the definitions specified inGSM 07.01.For interworking of data calls between a PLMN and a PSTN a modem will be utilized to provide theinterworking function.TEMTPLMNRAMODEMIWFPSTNMODEMV.seriesFigure 1: PLMN PSTN interworking for circuit switched calls9.2.1Network interworking mobile originated9.2.1.1Selection of interworking functionThe interworking function will need to negotiate with the user to establish the appropriate modem selectione.g. data rate, modulation scheme, etc. In addition, it will also be required to convert the signalling format,from a combination of out of band and in band, to that suitable for controlling the modem and theautocalling line procedure function where applicable. In the following modem selection procedures it isassumed that the interworking function and modems will be associated with each MSC. As an alternative,a centralized modem resource is possible as a network provider option. Signalling between the MSC andthe centralized modem resource is outside the scope of this specification.For a data call originated by a circuit mode data terminal on the PLMN, the modem selection is done byusing the element "modem type" in the call set-up message (bearer capability).In addition, other elements of the call setup will indicate the user rate, etc. to be used via that modem. Theuse of this information however means that the network is only able to select a modem from the modempool which conforms to the speed which the terminal is utilizing at the DTE/DCE interface at the MS(e.g. V.22 for 1 200 bps). The exception to this is where the user has selected the non transparent servicein which case either an autobauding or multi self selecting speed modem (e.g. V.32) may be used.In case the GSM-BC(s) received with the set-up message indicated a multislot or 14.4kbit/s-operation(refer to GSM 07.01) and the network does not support this service, the GSM-BC(s) sent with the callproceeding message shall not contain the “fixed network user rate”, “other modem type” and “userinitiated modification indicator” parameters - the MSC shall discard the multislot or 14.4kbit/s-relatedparameters and use the fall-back bearer service indicated by the remaining parameters of the GSM-BS(s)on a singleslot configuration (refer to GSM 08.20 and GSM 04.21) on the MSC/IWF-BSS link. TheMSC/IWF shall modify the relevant parameters in a possibly present LLC accordingly.If the MSC supports the multislot or 14.4kbit/s-operation, the GSM-BC(s) shall include the “fixed networkuser rate”, “other modem type” and if applicable the “user initiated modification indicator” parameters. TheMSC shall apply a singleslot configuration when the “maximum number of traffic channels” indicates ‘1TCH’ and the “user initiated modification indicator” indicates either ‘user initiated modification notrequested’ or ‘user initiated modification up to 1 TCH/F requested’, otherwise a multislot configuration(refer to GSM 08.20 and GSM 04.21) shall be used on the MSC/IWF-BSS link. In case the MS signals anACC containing TCH/F4.8 only and the network does not support TCH/F4.8 channel coding, then theMSC may act as if TCH/F9.6 were included in the ACC.In case the GSM-BC(s) received with the set-up message did not indicate a multislot or 14.4kbit/s-operation, the MSC shall not include the “fixed network user rate”, “other modem type” and “user initiatedSIST ETS 300 976 E6:2003

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