SIST ETS 300 604 E4:2003

• Abstract:

  ....

• Status: Published
• Publication Date: 30-Nov-2003
• ICS: 33.040.35 - Telephone networks
• ICS: 33.070.50 - Global System for Mobile Communication (GSM)
• ICS: 33.080 - Integrated Services Digital Network (ISDN)
• Technical Committee: SS EIT - Technical Board for the electrotechnical, information technology and telecommunications fields
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 01-Dec-2003
• Due Date: 01-Dec-2003
• Completion Date: 01-Dec-2003
• Ref Project: ETSI ETS 300 604 ed.4 (1996-05) - Digital 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)

SIST ETS 300 604 E4:2003 is the Slovenian adoption of ETS 300 604 Edition 4 from ETSI. It specifies the Mobile-services Switching Centre (MSC) Interworking Functions (IWFs) and related requirements for interworking between a GSM Phase 2 Public Land Mobile Network (PLMN) and the Public Switched Telephone Network (PSTN) or the Integrated Services Digital Network (ISDN).

What does SIST ETS 300 604 E4:2003 specify?

SIST ETS 300 604 E4:2003 covers how a PLMN interworks with the PSTN and ISDN for both voice and non-voice calls. The document treats PSTN and ISDN separately because the fixed-network access and signalling assumptions are different, especially for PSTN analogue access without D-channel signalling.

The standard is organized into:

• scope, references, definitions and introduction
• network characteristics
• interworking classifications
• compatibility and subscription checking
• PSTN interworking
• ISDN interworking
• V.110 frame synchronisation
• Annex A with informative SDLs

Annex	What it covers
Annex A	Informative SDLs intended to help interpret section 10.2.2

The core of the standard is in the interworking clauses. It separates speech calls from data calls, and it also addresses alternate speech/data handling and V.110 synchronisation behavior. That structure matters because network equipment, modem handling, and call-control logic are not the same for every call type.

What are the key requirements of SIST ETS 300 604 E4:2003?

SIST ETS 300 604 E4:2003 focuses on the functions the MSC/IWF must perform when a GSM PLMN connects to PSTN or ISDN. The most important requirements are the call-control checks, the bearer-service mapping, the modem and rate-adaptation behavior, and the handling of synchronisation.

Network characteristics and interworking model

Clause 6 distinguishes the network types by subscriber interface, signalling, transmission facilities, exchange type, transfer mode and information transfer capability. Clause 7 then classifies interworking into service interworking, network interworking, signalling interworking, numbering and supplementary service interworking. In practice, this tells the designer which part of the connection is being adapted - the service, the network bearers, the signalling, or the numbering plan.

Compatibility and subscription checking

Clause 8 requires compatibility checking on low layer compatibility and high layer compatibility using the relevant information elements. It also points subscription checking to GSM 02.01. For implementers, this means a call must not be passed through simply because signalling exists - the network must check whether the requested bearer and terminal characteristics match the allowed service and the subscriber’s rights.

PSTN interworking for data and speech

Clause 9 states that PSTN data interworking uses a modem as the interworking function. The MSC/IWF checks the bearer capability against the 3.1 kHz audio assumption for PSTN and rejects unsupported requests with an error cause when the requested service cannot be carried. This matters because PSTN support is constrained by analogue access and modem-based adaptation.

Clause 9 also separates transparent and non-transparent service support. Transparent service uses rate adaptation and terminal synchronisation handling, while non-transparent service adds protocol-layer functions such as re-constitution of user data, Layer 2 relay, flow-control mapping and buffers. In practice, equipment vendors must implement different data paths depending on whether the service is transparent or non-transparent.

PSTN alternate speech/data handling

Clause 9.3 covers alternate speech/data calls and speech followed by data. The document gives separate handling for mobile-originated and PSTN-originated cases. For network operators, this means the call-control logic must be able to switch the bearer handling according to the call sequence, not just the terminal type.

ISDN interworking and bearer mapping

Clause 10 uses the ISDN signalling model as the basis for interworking, with DSS1 and ISUP assumptions. For speech calls, the standard says no special interworking is required because the transcoder provides A-law PCM at 64 kbit/s. For data calls, the document assumes that the ISDN 3.1 kHz audio bearer is interworked by a modem pool in the PLMN.

The most detailed part of Clause 10 is the mapping between GSM 04.08 bearer capability content and the ETS 300 102-1 ISDN bearer capability fields. Tables 6A and 6B describe how values such as transfer mode, rate adaptation, modem type, user rate, parity, duplex mode and protocol-related fields map between the two systems. In practice, these tables are the implementation guide for HLR/VLR and MSC/IWF handling of bearer capability information.

Special handling for facsimile and alternate speech/data

Clause 10 gives special treatment to facsimile group 3 and to cases where compatibility information or high layer compatibility indicates fax-related service. It also states that alternate speech/unrestricted digital combinations are not applicable for ISDN interworking when unrestricted digital information is present. That matters because some GSM bearer combinations cannot be forwarded unchanged into ISDN and must be rejected or re-mapped.

V.110 frame synchronisation

Clause 11 defines how V.110 frame synchronisation is established and how loss of synchronisation is handled for transparent and non-transparent services. The MSC/IWF maintains separate expectations for the BSS/MSC side and the fixed-network side. In practice, this tells implementers what to do when framing is lost so that data transfer can continue or recover correctly without corrupting the other side of the connection.

What terms does SIST ETS 300 604 E4:2003 define?

SIST ETS 300 604 E4:2003 defines the following key terms for interworking decisions and bearer mapping:

• Bearer capability information - Information that defines the lower-layer characteristics needed within the network.
• Low layer compatibility information - Information that defines the terminal’s lower-layer characteristics.
• High layer compatibility information - Information that defines the terminal’s higher-layer characteristics.
• Compatibility information - The combined set of bearer capability, low layer compatibility, high layer compatibility, progress indicator and address information used before call establishment.
• Protocol identifier - Information that defines the protocol used for data transfer by a terminal.
• Progress indicator - Information that tells the terminal that network interworking has taken place.
• Out-of-band parameter exchange - Information exchanged over an associated or non-associated signalling link such as SS No.7.
• Autobauding type 1 - A non-transparent data case where the MSC/IWF may choose speed and modem type according to remote-modem negotiation within the user-speed limit.
• Multi self selecting speed modem - A V-series modem that can fall back to lower speeds and lets the MSC/IWF select the negotiated speed within the indicated limit.

Who uses SIST ETS 300 604 E4:2003?

SIST ETS 300 604 E4:2003 is used by telecom network engineers, switch and MSC/IWF designers, and GSM network operators who need to support calls between a PLMN and the PSTN or ISDN. It is also relevant to terminal adaptation and modem integration teams, because the document covers rate adaptation, modem selection, DTE/DCE filtering and synchronisation handling.

Quality managers and test teams use it to verify bearer-capability mapping, compatibility checking, subscription enforcement and the handling of transparent and non-transparent data services. Buyers and system integrators can use it to judge whether an MSC, gateway or interworking platform supports the call types and network behaviors they need.

Which standards are used with SIST ETS 300 604 E4:2003?

SIST ETS 300 604 E4:2003 relies on several companion standards for signalling, bearer services and terminal adaptation:

• CCITT G.711 - provides PCM voice coding for speech interworking.
• CCITT I.460 - covers multiplexing, rate adaptation and support of existing interfaces.
• CCITT V.25 - supports automatic answering and echo-control-related procedures.
• CCITT V.110 - provides DTE support over ISDN and is used for frame synchronisation behavior.
• ETS 300 102-1 - supplies ISDN basic call control and bearer capability coding used in the mapping tables.
• ETS 300 121 - covers ISUP for ISDN interconnections.
• GSM 01.04 - provides definitions, abbreviations and acronyms.
• GSM 02.01, GSM 02.02, GSM 02.03, GSM 02.04 - define services, bearer services, teleservices and supplementary services.
• GSM 03.03 and GSM 03.08 - cover numbering and subscriber data.
• GSM 04.08, GSM 04.21, GSM 04.22 - cover radio interface layer 3, rate adaptation and RLP.
• GSM 07.01, GSM 07.02, GSM 07.03 - cover terminal adaptation functions.
• GSM 08.20 and GSM 08.60 - cover BSS-MSC rate adaptation and inband control.
• GSM 09.03, GSM 09.05, GSM 09.06 - cover related interworking and packet-data topics.

What does the SIST ETS 300 604 E4:2003 document contain?

SIST ETS 300 604 E4:2003 contains comparison material for GSM PLMN, ISDN and PSTN network characteristics, plus detailed interworking procedures for speech and data. It includes tables that compare bearer services and teleservices across network types, and tables 6A and 6B that map GSM 04.08 bearer capability fields to ETS 300 102-1 fields for mobile-terminated call handling.

The document also contains detailed subsections for transparent and non-transparent service support, modem selection, DTE/modem interface filtering, Layer 2 relay behavior, flow control, data buffers, BREAK handling and end-to-end synchronisation. These sections are used for implementation, integration testing and network acceptance of MSC/IWF behavior.

Annex A provides SDLs for interpreting section 10.2.2. The annex is informative, so it supports understanding and design work rather than adding implementation requirements.

SLOVENSKI STANDARD
01-december-2003
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PHGVHERMQRGHORYDQMHPHGMDYQLPNRSHQVNLPPRELOQLPRPUHåMHP3/01LQ
GLJLWDOQLPRPUHåMHP]LQWHJULUDQLPLVWRULWYDPL,6'1DOLMDYQLPNRPXWLUDQLP
WHOHIRQVNLPRPUHåMHP3671*60
Digital 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)
Ta slovenski standard je istoveten z: ETS 300 604 Edition 4
ICS:
33.040.35 Telefonska omrežja Telephone networks
33.070.50 Globalni sistem za mobilno Global System for Mobile
telekomunikacijo (GSM) Communication (GSM)
33.080 Digitalno omrežje z Integrated Services Digital
integriranimi storitvami Network (ISDN)
(ISDN)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN ETS 300 604
TELECOMMUNICATION May 1996
STANDARD Fourth Edition
Source: ETSI TC-SMG Reference: RE/SMG-040907PR3
ICS: 33.060.50
Digital cellular telecommunications system, Global System for Mobile communications (GSM)
Key words:
Digital cellular telecommunications system (Phase 2);
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)
ETSI
European Telecommunications Standards Institute
ETSI Secretariat
F-06921 Sophia Antipolis CEDEX - FRANCE
Postal address:
650 Route des Lucioles - Sophia Antipolis - Valbonne - FRANCE
Office address:
c=fr, a=atlas, p=etsi, s=secretariat - [e-mail]
X.400: Internet:
Tel.: [phone] - Fax: [phone]
*
Copyright Notification: No part may be reproduced except as authorized by written permission. The copyright and the
foregoing restriction extend to reproduction in all media.
© European Telecommunications Standards Institute 1996. All rights reserved.

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ETS 300 604: May 1996 (GSM 09.07 version 4.10.0)
Whilst every care has been taken in the preparation and publication of this document, errors in content,
typographical or otherwise, may occur. If you have comments concerning its accuracy, please write to
"ETSI Editing and Committee Support Dept." at the address shown on the title page.

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ETS 300 604: May 1996 (GSM 09.07 version 4.10.0)
Contents
Foreword .7
1 Scope .9
2 Normative references.9
3 Definitions and abbreviations .11
4 Introduction.12
5 Not used.14
6 Network Characteristics .14
6.1 Key Characteristics of Networks Concerned .14
6.1.1 Characteristics of PLMNs.14
6.1.2 Characteristics of PSTNs .14
6.1.3 Characteristics of ISDN.15
7 Interworking classifications .15
7.1 Service interworking.15
7.2 Network interworking .15
7.3 Signalling interworking .18
7.4 Numbering .18
7.5 Supplementary service interworking.18
8 Compatibility and subscription checking .18
9 Interworking to PSTN .18
9.1 Speech Calls.18
9.1.1 Interworking indications to PLMN terminal.18
9.1.2 Transmission aspects .19
9.1.3 Generation of In-band Tones and Announcements (PLMN-PSTN).19
9.2 Data Calls .19
9.2.1 Network interworking mobile originated .19
9.2.1.1 Selection of interworking function.19
9.2.1.2 Modem Selection.20
9.2.1.3 DTE/Modem interface (Filtering) .20
9.2.1.4 Mapping of BC-IE from GSM 04.08 to ISUP (or other).21
9.2.2 Network Interworking Mobile terminated PSTN Originated.21
9.2.3 Transparent service support .25
9.2.3.1 Not used .25
9.2.3.2 Rate adaptation process in MSC/IWF .25
9.2.3.3 Mapping of signalling MS/MSC/IWF to modem interface
requirements.25
9.2.3.4 Establishment of end-to-end terminal synchronizations .26
9.2.3.5 Network Independent Clocking (NIC).26
9.2.4 Non-transparent service support.27
9.2.4.1 MSC-IWF Rate adaptation scheme.27
9.2.4.2 Protocol layer structure in the MSC/IWF .27
9.2.4.3 Re-constitution of user data.27
9.2.4.4 Layer 2 relay functionality .27
9.2.4.5 In band signalling mapping flow control.28
9.2.4.5.1 Conditions requiring flow control
towards the fixed network .28
9.2.4.5.2 Conditions requiring flow control
towards the MS.28

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ETS 300 604: May 1996 (GSM 09.07 version 4.10.0)
9.2.4.6 Data buffers . 29
9.2.4.6.1 Transmit buffers (towards MS). 29
9.2.4.6.2 Receive buffers (from MS) . 29
9.2.4.7 Transportation of the Break condition. 29
9.2.4.8 In band signalling mapping modem status information. 29
9.2.4.9 Support of out-band flow control . 29
9.2.4.10 Establishment of end-to-end terminal synchronizations . 29
9.3 Interworking Alternate Speech / Data Calls. 31
9.3.1 Alternate Speech/Data Interworking. 31
9.3.1.1 General . 31
9.3.1.2 Mobile originated PSTN terminated calls. 31
9.3.1.3 PSTN originated mobile terminated calls. 31
9.3.2 Speech followed by data interworking . 32
9.3.2.1 General . 32
10 Interworking to the ISDN. 32
10.1 Speech Calls . 32
10.2 Data Calls. 32
10.2.1 Network interworking mobile originated. 33
10.2.1.1 Circuit switched calls. 33
10.2.1.2 Packet calls. 33
10.2.2 Network interworking mobile terminated . 34
10.2.2.1 Circuit switched calls. 49
10.2.2.2 Packet calls. 49
10.2.3 Transparent service support (see GSM 03.10) . 49
10.2.3.1 MSC - IWF rate adaptation scheme . 49
10.2.3.2 Rate adaptation process in MSC/IWF . 49
10.2.3.3 Mapping of signalling MS/MSC/IWF to modem interface
requirements . 49
10.2.3.4 Establishment of end-to-end terminal synchronizations . 50
10.2.3.5 Network independent Clocking (NIC). 51
10.2.4 Non-transparent service support (See GSM 03.10) . 51
10.2.4.1 MSC - IWF Rate adaptation scheme. 51
10.2.4.2 Protocol layer structure in the MSC/IWF. 51
10.2.4.3 Re-constitution of user data . 51
10.2.4.4 Layer 2 relay functionality. 51
10.2.4.5 In band signalling mapping flow control . 52
10.2.4.5.1 Conditions requiring flow control - if
flow control is provided -towards the
fixed network . 52
10.2.4.5.2 Conditions requiring flow control
towards the MS . 52
10.2.4.6 Data buffers . 53
10.2.4.6.1 Transmit buffers (towards MS). 53
10.2.4.6.2 Receive buffers (from MS) . 53
10.2.4.7 BREAK Indication. 53
10.2.4.8 Signalling mapping modem status information or in band
rate adapted frame information. 53
10.2.4.9 Support of out-band flow control . 53
10.2.4.10 Synchronisations. 53
10.2.4.10.1 V110 Frame synchronisations. 53
10.2.4.10.2 RLP Frame start indication. 53
10.2.4.10.3 L2R Frame synchronizations. 54
10.2.4.10.4 Establishment of end-to-end terminal
synchronizations. 54
10.2.5 DTE/Modem interface (Filtering) . 54
10.3 Interworking Alternate speech data calls . 55
10.3.1 Alternate speech data bearer interworking. 55
10.3.1.1 General . 55
10.3.1.2 Mobile originated ISDN terminated . 56
10.3.1.3 ISDN originated mobile terminated . 56
10.3.2 Speech followed by data interworking . 56
10.3.2.1 General . 56

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ETS 300 604: May 1996 (GSM 09.07 version 4.10.0)
11 V.110 Frame Synchronisation.57
11.1 Initial V.110 frame synchronisation.57
11.2 Action on loss of V.110 frame synchronisation for non transparent services .57
11.3 Action on loss of V.110 frame synchronisation for transparent services .57
Annex A (informative): SDLs.58
History.61

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ETS 300 604: May 1996 (GSM 09.07 version 4.10.0)
Foreword
This European Telecommunication Standard (ETS) was produced by the Special Mobile Group (SMG)
Technical Committee of the European Telecommunications Standards Institute (ETSI).
This ETS identifies the Mobile-services Switching Centre (MSC) Interworking Functions (IWFs) and
requirements to support interworking between:
a) Public Land Mobile Network (PLMN) and Public Switched Telephone Network (PSTN);
b) PLMN and Integrated Services Digital Network (ISDN).
This ETS corresponds to GSM technical specification GSM 09.07 version 4.10.0
The specification from which this ETS has been derived was originally based on CEPT documentation,
hence the presentation of this ETS may not be entirely in accordance with the ETSI/PNE rules.
Reference is made within this ETS to GSM-TSs (note).
Reference is also made within this ETS to GSM xx.xx. series. The specifications in the series can be
identified, with their full title, within the normative reference clause of this ETS by the first two digits of their
GSM reference number e.g. GSM 09.xx series, refers to GSM 09.01, GSM 09.02, etc.
NOTE: TC-SMG has produced documents which give the technical specifications for the
implementation of the European digital cellular telecommunications system.
Historically, these documents have been identified as GSM Technical Specifications
(GSM-TSs). These ETSs may have subsequently become I-ETSs (Phase 1), or ETSs
(Phase 2), whilst others may become ETSI Technical Reports (ETRs). GSM-TSs are,
for editorial reasons, still referred to in current GSM ETSs.
Proposed transposition dates
Date of adoption of this ETS: 30 April 1996
Date of latest announcement of this ETS (doa): 20 August 1996
Date of latest publication of new National Standard
or endorsement of this ETS (dop/e): 18 February 1997
Date of withdrawal of any conflicting National Standard (dow): 18 February 1997

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ETS 300 604: May 1996 (GSM 09.07 version 4.10.0)
1 Scope
The purpose of this European Telecommunication Standard (ETS) is to identify the Mobile-services
Switching Centre (MSC)/Interworking Functions (IWFs) and requirements to support interworking
between:
i) PLMN and PSTN
ii) PLMN and ISDN
It is not possible to treat ISDN and PSTN as one type of network, even when both ISDN and PSTN
subscribers are served by the same exchange because of the limitations of the PSTN subscribers access
ie analogue connection without D-channel signalling.
Within this ETS, the requirements for voice and non-voice (data) calls are considered separately.
2 Normative references
This ETS incorporates by dated and undated reference, provisions from other publications. These
normative references are cited at the appropriate places in the text and the publications are listed
hereafter. For dated references, subsequent amendments to or revisions of any of these publications
apply to this ETS only when incorporated in it by amendment or revision. For undated references, the
latest edition of the publication referred to applies.
[1] CCITT Recommendation G.711: "Pulse code modulation (PCM) of voice
frequencies".
[2] CCITT Recommendation I.460: "Multiplexing, rate adaption and support of
existing interfaces".
[3] CCITT Recommendation V.25: "Automatic answering equipment and/or parallel
automatic calling equipment on the general switched telephone network
including procedures for disabling of echo control devices for both manually and
automatically established calls".
[4] CCITT Recommendation V.110: "Support of data terminal equipments (DTEs)
with V-Series interfaces by an integrated services digital network".
[5] ETS 300 102-1: "Integrated Services Digital Network (ISDN); User-network
interface layer 3 Specifications for basic call control".
[6] ETS 300 121: "Integrated Services Digital Network (ISDN); Application of the
ISDN User Part (ISUP) of CCITT Signalling System No.7 for international ISDN
interconnections (ISUP version 1)".
[7] GSM 01.04 (ETR 100): "European digital cellular telecommunication system
(Phase 2); Definitions, abbreviations and acronyms".
[8] GSM 02.01 (ETS 300 500): "European digital cellular telecommunication system
(Phase 2); Principles of telecommunication services supported by a GSM Public
Land Mobile Network (PLMN)".
[9] GSM 02.02 (ETS 300 501): "European digital cellular telecommunication system
(Phase 2); Bearer Services (BS) supported by a GSM Public Land Mobile
Network (PLMN)".
[10] GSM 02.03 (ETS 300 502): "European digital cellular telecommunication system
(Phase 2); Teleservices supported by a GSM Public Land Mobile Network
(PLMN)".
[11] GSM 02.04 (ETS 300 503): "European digital cellular telecommunication system
(Phase 2); General on supplementary services".

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ETS 300 604: May 1996 (GSM 09.07 version 4.10.0)
[12] GSM 02.81 (ETS 300 514): "European digital cellular telecommunication system
(Phase 2); Line identification supplementary services - Stage 1".
[13] GSM 02.82 (ETS 300 515): "European digital cellular telecommunication system
(Phase 2); Call Forwarding (CF) supplementary services - Stage 1".
[14] GSM 02.83 (ETS 300 516): "European digital cellular telecommunication system
(Phase 2); Call Waiting (CW) and Call Hold (HOLD) supplementary services -
Stage 1".
[15] GSM 02.84 (ETS 300 517): "European digital cellular telecommunication system
(Phase 2); MultiParty (MPTY) supplementary services - Stage 1".
[16] GSM 02.85 (ETS 300 518): "European digital cellular telecommunication system
(Phase 2); Closed User Group (CUG) supplementary services - Stage 1".
[17] GSM 02.86 (ETS 300 519): "European digital cellular telecommunication system
(Phase 2); Advice of charge (AoC) supplementary services - Stage 1".
[18] GSM 02.88 (ETS 300 520): "European digital cellular telecommunication system
(Phase 2); Call Barring (CB) supplementary services - Stage 1".
[19] GSM 03.03 (ETS 300 523): "European digital cellular telecommunication system
(Phase 2); Numbering, addressing and identification".
[20] GSM 03.08 (ETS 300 526): "European digital cellular telecommunication system
(Phase 2); Organisation of subscriber data".
[21] GSM 03.11 (ETS 300 529): "European digital cellular telecommunication system
(Phase 2); Technical realization of supplementary services".
[22] GSM 03.45 (ETS 300 538): "European digital cellular telecommunication system
(Phase 2); Technical realization of facsimile group 3 transparent".
[23] GSM 03.46 (ETS 300 539): "European digital cellular telecommunication system
(Phase 2); Technical realization of facsimile group 3 non-transparent".
[24] GSM 03.50 (ETS 300 540): "European digital cellular telecommunication system
(Phase 2); Transmission planning aspects of the speech service in the GSM
Public Land Mobile Network (PLMN) system".
[25] GSM 04.08 (ETS 300 557): "European digital cellular telecommunication system
(Phase 2); Mobile radio interface layer 3 specification".
[26] GSM 04.21 (ETS 300 562): "European digital cellular telecommunication system
(Phase 2); Rate adaption on the Mobile Station - Base Station System (MS -
BSS) interface".
[27] GSM 04.22 (ETS 300 563): "European digital cellular telecommunication system
(Phase 2); Radio Link Protocol (RLP) for data and telematic services on the
Mobile Station - Base Station System (MS - BSS) interface and the Base Station
System - Mobile-services Switching Centre (BSS - MSC) interface".
[28] GSM 07.01 (ETS 300 582): "European digital cellular telecommunication system
(Phase 2); General on Terminal Adaptation Functions (TAF) for Mobile Stations
(MS)".
[29] GSM 07.02 (ETS 300 583): "European digital cellular telecommunication system
(Phase 2); Terminal Adaptation Functions (TAF) for services using
asynchronous bearer capabilities".

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[30] GSM 07.03 (ETS 300 584): "European digital cellular telecommunication system
(Phase 2); Terminal Adaptation Functions (TAF) for services using synchronous
bearer capabilities".
[31] GSM 07.05 (ETS 300 585): "European digital cellular telecommunication system
(Phase 2); Use of Data Terminal Equipment - Data Circuit terminating
Equipment (DTE - DCE) interface for Short Message Service (SMS) and Cell
Broadcast Service (CBS)".
[32] GSM 08.20 (ETS 300 591): "European digital cellular telecommunication system
(Phase 2); Rate adaption on the Base Station System - Mobile-services
Switching Centre (BSS - MSC) interface".
[33] GSM 08.60 (ETS 300 597): "European digital cellular telecommunication system
(Phase 2); Inband control of remote transcoders and rate adaptors".
[34] GSM 09.02 (ETS 300 599): "European digital cellular telecommunication system
(Phase 2); Mobile Application Part (MAP) specification".
[35] GSM 09.03 (ETS 300 600): "European digital cellular telecommunication system
(Phase 2); Signalling requirements on interworking between the Integrated
Services Digital Network (ISDN) or Public Switched Telephone Network (PSTN)
and the Public Land Mobile Network (PLMN)".
[36] GSM 09.05 (ETS 300 602): "European digital cellular telecommunication system
(Phase 2); Interworking between the Public Land Mobile Network (PLMN) and
the Packet Switched Public Data Network (PSPDN) for Packet
Assembly/Disassembly facility (PAD) access".
[37] GSM 09.06 (ETS 300 603): "European digital cellular telecommunication system
(Phase 2); Interworking between a Public Land Mobile Network (PLMN) and a
Packet Switched Public Data Network/Integrated Services Digital Network
(PSPDN/ISDN) for the support of packet switched data transmission services".
NOTE: As regards ETS 300 102-1 [5], the edition 1 of this ETS from 1990 shall be used, with
one exception: the encoding of the field modem type in the ISDN BC-IE shall be
handled as specified in table 6A and 6B of GSM 09.07.
3 Definitions and abbreviations
Use is made of the following terms within this ETS. These terms refer to information requirements
necessary to support interworking functions, some of these terms will be identifiable with their use in other
GSM TS.
- Bearer capability information
Specific information defining the lower layer characteristics required within the network.
- Low layer compatibility information
Information defining the lower layer characteristics of the terminal.
- High layer compatibility information
Information defining the higher layer characteristics of the terminal.
- Compatibility information
This term subsumes the entirety of Bearer Capability, Low Layer Compatibility, High Layer
Compatibility, Progress Indicator and Address Information conveyed out-of-band prior to call
establishment for the support of compatibility checking and terminal/function/service selection at the
ISDN-type user-network interface.
- Protocol identifier
Information defining the specific protocols utilised for the support of data transfer by a terminal.

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ETS 300 604: May 1996 (GSM 09.07 version 4.10.0)
- Progress indicator
Information supplied to indicate to the terminal that network interworking has taken place.
- Out-of-band parameter exchange
Information exchanged via an associated or non-associated signalling 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 standardised user to
network associated signalling system and a standardised internetwork signalling system.
- Autobauding type 1
This information element value may be contained in the setup or call confirm messages from the
mobile station in association with a non transparent data service. This implies that the MSC/IWF
may select any speed and modem type according to what it can negotiate with the remote modem
on the PSTN/ISDN. The maximum speed to be used by the MSC/IWF is the user speed indicated in
the setup/call confirm message.
- Multi self selecting speed modem
This term applies to V series modems capable of handling one or more lower speeds as a fall back
position. When such a modem is requested in the call setup or call confirm message from the MS
in association with a non transparent service, the MSC/IWF may select any of the speeds
supported according to the negotiation with the remote modem on the PSTN/ISDN. In this instance
the maximum starting negotiation speed to be used by the MSC/IWF is the one indicated by the
user speed in the setup/call confirm message.
In addition to those below abbreviations used in this specification are listed in GSM 01.04.
ADPCM Adaptive Differential Pulse Coded Modulation
DP Dial Pulse
ITC Information Transfer Capability
LE Local Exchange
NT Network Termination
PABX Private Automatic Branch Exchange
SPC Stored Program Control
SS No.7 Signalling System No.7
TE Terminal Equipment
TA Terminal Adaptor
TUP Telephone User Part (of Signalling System No.7)
DSS1 Digital Subscriber Signalling 1
UNI User Network Interface
4 Introduction
General Network Interworking Scenarios are described in GSM 09.01. Since the numbering plan for the
ISDN era (E.164) includes the numbering plan for the telephone network (E.163), it is not possible to

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distinguish by the number whether a given subscriber is a PSTN or ISDN subscriber. Further, in some
countries both PSTN and ISDN subscribers will be connected to the same exchange, so the only
difference for this type of combined network will be in the nature of the customer access. In this document
a PSTN is considered to support only an analogue interface towards the subscriber. An ISDN shall be
considered to support digital interface towards the subscriber. In addition, the ISDN is considered to
support a standardised outband signalling protocol both between the subscriber and the network and
within the network, i.e DSS1 and ISUP, thus enabling the generation and transport of Compatibility
Information for compatibility checking and terminal/function/service selection at the user-network interface
as well as for MSC/IWF selection.
There now exist networks which do not fall into either of these categories in that they provide for digital
connectivity from subscriber to subscriber through the network. The subscribers have access to a wide
range of services by a limited set of standard multi-purpose user network interfaces. However, these
networks do not support the standardised inter-exchange signalling protocol throughout, in that they are
e.g using TUP or National User Part (NUP). These types of network support 64kbit/s connections, so in
service support are comparable to ISDN, however, the signalling system provided may not support
transport of all Compatibility Information allowed for in the standardised ISDN signalling. This document
will therefore identify interworking to PSTN and ISDN on the principle of the network characteristics as
identified in the previous paragraph. The aforementioned existing networks then constitute one particular
case in the ISDN interworking scenarios. These cases will be itemised when the implication of the various
degrees of exhaustiveness of the Compatibility Information - delivered via the ISDN - used for deducting a
GSM Basic Service needs to be set forth.
When two dissimilar networks are required to interwork in order to support a communication between two
subscribers, one on each network, a number of Interworking Functions (MSC/IWFs) are required to
support the communication. Some of these are related to the differences in signalling and are dealt with in
GSM 09.03.
Examples of other aspects of interworking are:
i) the need or otherwise of echo control devices
ii) 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 separately
each type of interworking (ie PLMN-ISDN and PLMN-PSTN) since, in the worst case, "PSTN" could refer
to an essentially analogue network with electromechanical switching not controlled by software and
without common-channel signalling.
Some facilities associated with alternate speech and data may not be available with version 1 of the MAP.
Version 1 of the Mobile Application Part (MAP) does not support transfer between the HLR and VLR, and
VLR and VMSC of multiple bearer capabilities. In addition, version 1 of the MAP does not support in-call
modification and channel mode modification following an inter-MSC handover.

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5 Not used
6 Network Characteristics
6.1 Key Characteristics of Networks Concerned
TABLE 1/09.07: Key Characteristics of Networks Concerned
Characteristic GSM PLMN ISDN PSTN
Subscriber Interface Digital Digital Analogue
User-network signalling GSM 04.08 DSS1, other UNIs loop-disconnect and DTMF
User-terminal equipment MT0, MT1 or MT2Digital TE Analogue TE (eg. dial pulse
supported functions (see GSM (ISDN NT, TE1 or telephones PABXs modem
04.02) TE2+TA) equipped DTEs)
see e.g. I.411
Inter-exchange signalling SS No.7 ISUP TUP+, SS No.7 ISUPChannel associated
MAP TUP+, TUP, NUP (e.g. R2, No.4, No.5) or
common channel (e.g. No.6)
Transmission facilities Digital Digital Analogue
Exchange types Digital Digital Analogue/digital
Information transfer mode Circuit Circuit/Packet Circuit
Information transfer capability Speech, digital Speech, digital3.1 kHz audio
unrestricted, alternate unrestricted, 3.1 (voice/voice- band data)
speech/ group 3 fax etc. kHz audio, video
etc.
6.1.1 Characteristics of PLMNs
The GSM PLMN is fully defined in the GSM Technical Specifications.
6.1.2 Characteristics of PSTNs
Because of the efforts at an early stage to standardize ISDNs in different countries, the differences
between any two ISDNs will be small compared with the differences between PSTNs, which have evolved
in different ways in different countries. In some cases the evolution has occurred over many decades, and
therefore each PSTN is distinct, and for a recommendation on interworking, it is necessary to make
certain assumptions about a generalized PSTN.
Whilst the key characteristics of PSTNs are given in Table 1 above, the specific MSC/IWFs needed to
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 of
possibilities within each category.

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TABLE 2/09.07: Characteristics of PSTNs
Category Possibilities within Category
Type of subscriber a) PSTN with loop disconnect subscriber signalling (10 pps)
signalling b) PSTN with DTMF subscriber signalling
Type of interexchange a) PSTN with channel-associated signalling
signalling b) PSTN with common-channel signalling
Type of interexchange a) Analogue
transmission b) Digital
Type of exchange a) PSTN with electro-mechanical switching
switching b) PSTN with electronic (non-digital) switching
c) PSTN with electronic digital switching
Type of exchange a) Non-SPC
control b) SPC
NOTE: Under each category, it is possible that a PSTN will have a combination of the
possibilities rather than only one.
6.1.3 Characteristics of ISDN
For the "standardised ISDN" in principle taken into account here, these are defined in the ETS-series.
7 Interworking classifications
7.1 Service interworking
Service interworking is required when the Teleservices at the calling and called terminals are different. No
service interworking, except for facsimile group 3 (GSM Teleservice 61 or 62 interworking with standard
facsimile group 3 service), has been identified as a requirement of the GSM system for PSTN/ISDN
network based services.
7.2 Network interworking
Network interworking is required whenever a PLMN and a non-PLMN together are involved to provide an
end 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. A
bearer service is defined (in GSM 02.01) as:
A type of telecommunication service that provides the capability for the transmission of signals between
user-network interfaces.
Bearer services are described by a number of attributes, where an attribute is defined as a specified
characteristic of an object or element whose values distinguish that object or element from others.
For the purpose of this ETS, a PSTN is assumed to provide a bearer service which equates to an ISDN
3.1 kHz audio bearer service.
Refer to GSM 02.02 for complete list of bearer services. Refer to GSM 04.08 for coding of Bearer
Capabilities.
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TABLE 3/09.07 Bearer Service Interworking
Bearer service category in GSM Bearer Service in GSM Bearer service in Service in PSTN
PLMN ISDN
Circuit mode unstructured with
Asynchronous Data 300 bit/s
unrestricted digital capability
Asynchronous Data 1.2 kbit/s
Transparent and
Asynchronous Data 1200/75 bit/s Not Applicable
Non transparent
Cct mode
Asynchronous Data 2.4 kbit/s
structured 64 kbit/s
unrestricted
Asynchronous Data 4.8 kbit/s
Asynchronous Data 9.6 kbit/s
Circuit mode unstructured with
Synchronous Data 1.2 kbit/s
unrestricted digital capabilitiy
Transparent
Synchronous Data 2.4 kbit/s
Synchronous Data 4.8 kbit/s
Synchronous Data 9.6 kbit/s
Circuit mode unstructured withPacket Services Packet Services
unrestriced digital capability. see GSM 09.06 see GSM 09.06
Non-transparent
3.1 kHz Audio Ex PLMN
Asynchronous Data 300 bit/s
Transparent and Non-transparent
Cct Mode
Asynchronous Data 1.2 kbir/s
3.1 kHz Audio
Asynchronous Data 1200/75 bit/s
Cct Mode
3.1 kHz Audio
Asynchronous Data 2.4 kbit/s
Asynchronous Data 4.8 kbit/s
Asynchronous Data 9,6 kbit/s
3.1 kHz Audio Ex PLMN Synchronous Data 1.2 kbit/s
Transparent Synchronous Data 2.4 kbit/s
Synchronous Data 4.8 kbit/s
Synchronous Data 9.6 kbit/s
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TABLE 3/09.07 Bearer Service Interworking (cont'd)
3.1 kHz Audio Ex PLMN
See GSM 09.06 See GSM 09.06
Non Transparent
Bearer service categoryBearer Service Bearer service Service
in GSM PLMN in GSM PLMN in ISDN in PSTN
Alternate speech /data circuitalternate speech/
mode unstructured with 3.1 kHzasynchronous
audio ex PLMN (with user rates 300 to
Tranparent 9600 bit/s as above)
alternate speech/
synchronous
(with user rates 1200 to
9600 bit/s as above)
Cct modeCct mode
Alternate speech/data circuitalternate speech/
3.1 kHz Audio 3.1 kHz Audio
mode unstructured with 3.1 kHzasynchronous
audio ex PLMN (with user rates 300 to
non transparent 9600 bit/s as above)
Circuit mode with speech followed Cct mode speech followed byCct mode
by data data 3.1 kHz audio
Transparent and Non transparent 300 to 9600 bit/s
asynchronous as above
TABLE 4/09.07 Network interworking of GSM Teleservices
Teleservice inLower layer capabilitiesBearer service Service
GSM PLMN addressed in the GSM Bearer in ISDN in PSTN
Capablities IE
Telephony Unstructured with speech capability Specch or Cct mode Cct Mode
Emergency calls Unstructured with speech capability 3.1 kHz audio 3.1 kHz audio
Alternate speech/ Data Cct duplex synchronous access Cct mode 3.1 kHz Cct mode 3.1 kHz
facsimile group 3alternate speech audio audio
group 3 fax
Automatic Data Cct duplex synchronous access Cct mode 3.1 kHz
Facsimile group 3 group 3 fax audio
This table does not identify any relationship between Teleservices in the GSM PLMN with those in the
ISDN/PSTN, it is merely to identify the interworking of the lower network layers of that teleservice with the
network layers i.e. bearer service in the ISDN/PSTN.

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7.3 Signalling interworking
See GSM 09.03.
7.4 Numbering
See GSM 03.03.
7.5 Supplementary service interworking
For general aspects of supplementary services refer to GSM 03.11, GSM 03.8x and 03.9x series.
Not every supplementary service may be used in combination with each basic service. The applicability of
each supplementary service for a basic service is defined in GSM 02.8x and 02.9x-series. Certain
application rules are also set out in GSM 02.03, 09.05 and 09.06.
This section only deals with data service specific aspects of supplementary services, i.e. MSC/IWF
functions concerned in combination with supplementary services. This interworking is described in GSM
02.04, GSM 02.8x, and 02.9x-series, GSM 03.11, GSM 03.8x and GSM 03.9x-series, if applicable.
8 Compatibility and subscription checking
Compatibility checking is carried out on the following items:
a) Low layer compatibility - utilising low layer compatibility and bearer capability information elements.
b) High layer compatibility - utilising 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 section 9.2.2 under "a) Functional
operation" or "b) Mobile subscriber indicates requirement in call confirmation message" and section 10.2.2
"Network interworking mobile terminated".
For subscription checking, relevant for the interworking described in sections 9 and 10 of this ETS, refer to
GSM 02.01.
9 Interworking to PSTN
9.1 Speech Calls
9.1.1 Interworking indications to PLMN terminal
An indication to inform the PLMN terminal that:
i) instead of receiving out-of-band indications for certain types of failure conditions, a tone or
announcement will be received in-band from the PSTN.
ii) the available compatibility information will be not exhaustive for deducing a GSM Basic Service and
there will be a limitation on address - the terminal may be required to accept the call on the basis of
indicating its compatibility requirements.
iii) (if a DTE) in-band handshaking signals should be anticipated.

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9.1.2 Transmission aspects
Includes control of Speech Processing and Echo Control Devices, see GSM 03.50.
9.1.3 Generation 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 services
between a PLMN and a PSTN.
9.2 Data Calls
Low Layer Compatibility Checking on the received GSM bearer capability information element will be
carried 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 capability
value "unrestricted digital information" is requested), the call shall fail with an error cause indicating that
the network is unable to support the service requested.
As well as compatibility checking subscription checking shall be performed. If the subscription check fails
the 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 in GSM
07.01.
For interworking of data calls between a PLMN and a PSTN a modem will be utilised to provide the
interworking function.
PLMN
TE M T RA MODEM PSTN MODEM
IW F
V.series
Figure 1: PLMN PSTN interworking for circuit switched calls
9.2.1 Network interworking mobile originated
9.2.1.1 Selection of interworking function
The interworking function will need to negotiate with the user to establish the appropriate modem selection
e.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 the
autocalling line procedure function where applicable. In the following modem selection procedures it is
assumed 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 and
the 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 by
using 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. The
use of this information however means that the network is only able to select a modem from the modem
pool which conforms to the speed which the terminal is utilising at the DTE/DCE interface at the mobile
station (e.g. V.22 for 1200bps). The exception to this is where the user has selected the non transparent
service in which case either an autobauding or multi self selecting speed modem (e.g V.32) may be used.

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9.2.1.2 Modem Selection
In general terms the indication of the bearer capability parameter "Information Transfer Capability" will be
utilised in the call set-up message to determine when the modem should be selected in the call.
In case of single calls, the modem function shall operate in the calling mode in case of mobile originated
calls and in the answering mode in case of mobile terminated calls.
In case of dual data calls (alternate speech/data, speech followed by data) the operation mode of the
modem (working in calling or answering mode) depend on the initial call setup direction and on the
...