Abstract

This ETS defines the interfaces and Terminal Adaptation Functions (TAF) integral to a Mobile Termination (MT) which enables the attachment of asynchronous terminals to a MT (see GSM 04.02 [4]). The general aspects of Terminal Adaptation Functions are contained in GSM 07.01 (ETS 300 913.

Status
Published
Publication Date
30-Nov-2003
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
01-Dec-2003
Due Date
01-Dec-2003
Completion Date
01-Dec-2003

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SIST ETS 300 914 E3:2003

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SIST ETS 300 914 E3:2003 is a European Telecommunications Standard from ETSI for GSM Phase 2+ mobile equipment. It specifies Terminal Adaptation Functions (TAF) for asynchronous bearer capabilities, so a Mobile Termination (MT) can attach asynchronous terminals and map their signalling, rate adaptation, flow control and call-control behavior into the GSM environment.

What does SIST ETS 300 914 E3:2003 specify?

SIST ETS 300 914 E3:2003 defines the interfaces and TAF inside an MT for asynchronous terminals, with coverage for TE1 and TE2 attachment in the GSM Phase 2+ reference configuration. It brings together the functions needed to make asynchronous user equipment work over transparent and non-transparent GSM bearer services.

The document is organized around:

  • Clause 1 - scope, references and abbreviations
  • Clause 2 - reference configuration and the main TAF functions
  • Clause 3 - TAF for transparent services
  • Clause 4 - TAF for non-transparent services
  • Clause 5 - terminal interfacing to GSM 04.08 mapping
  • Clause 6 - support for Dedicated PAD services
  • Annex A - normative L2R Functionality
  • Annex B - informative use of the 9 pin version of V.24 as an MT2 type
AnnexWhat it covers
Annex AL2R Functionality, including L2RCOP, status transfer, flow control and break handling
Annex BUse of the 9 pin version of V.24 as an MT2 type

Clause 1 also states that the document covers V.14, V.21, V.22bis, V.23, V.32, I.420, V.25bis and V.25ter related support, and that asynchronous data rates between the MT and TE2 come from GSM 02.02. In practice, that means the standard is aimed at implementations that must interwork with those terminal interfaces and signalling procedures.

What are the key requirements of SIST ETS 300 914 E3:2003?

SIST ETS 300 914 E3:2003 requires the MT TAF to perform the conversions and mappings needed for asynchronous services, not just pass bits through. The practical effect is that the MT must translate between terminal-side behavior and GSM-side bearer and signalling behavior.

  • Clause 2.2 says the TAF must convert electrical, mechanical, functional and procedural characteristics of V series and ISDN type interfaces into what the PLMN uses. This matters because the terminal-side interface is not the same as the radio-side service model.
  • Clause 2.2 includes rate adaptation for V series and ISDN 64 kbit/s data rates, plus mapping for automatic calling and answering. In practice, the implementation must match the service type to the correct adapted rate and call setup behavior.
  • Clause 2.2 includes mapping of S interface signalling to the PLMN Dm channel signalling, flow control, Layer 2 Relaying (L2R), in-call modification, synchronization, filtering of channel control information, terminal compatibility checking, and splitting/combining multislot data flows. These are the core interoperability tasks that keep calls and data sessions aligned across the GSM link.
  • Clause 3.2 and 3.3 require V.24 interchange circuit signalling mapping and interface signal levels that conform to V.28, IrDA IrPHY, PCMCIA 2.1, PC-Card 3.0 or later revisions. This tells implementers what electrical and control interfaces the equipment may use.
  • Clause 3.4 maps call establishment for autocalling and auto-answering using V.25 bis or V.25 ter, and manual operation for alternate speech/data and unrestricted digital capability. That means the terminal must support both automatic and user-driven call control paths.
  • Clause 4 requires V.24 flow control to support both inband XON/XOFF and out-of-band control through CT106 and CT133, with special handling when character-orientated protocol with no flow control is used. This matters because congestion on either side must be handled without losing data.
  • Clauses 4.4 to 4.7 require TX and RX buffering, bit transparency behavior, BREAK transport, and V.42bis data compression with RLP providing the error correction function. In practice, buffer sizing, break handling and compression state recovery are implementation-critical.
  • Clause 6 requires Dedicated PAD access to use a Private Number Plan and a Type of Number of Dedicated PAD, with the called number as a short code per GSM 09.05. This is the dialing information needed for PAD-specific access.

What terms does SIST ETS 300 914 E3:2003 define?

  • Terminal Adaptation Function (TAF) - The set of functions inside the MT that adapts asynchronous terminal behavior to GSM bearer and signalling behavior.
  • Mobile Termination (MT) - The GSM termination that contains the TAF and provides the attachment point for the terminal.
  • TE2 - The terminal side equipment addressed by the V.24-based interface and flow-control rules in this standard.
  • Layer 2 Relaying (L2R) - The relay function that carries characters, status information, flow control and break conditions between the terminal side and the radio side.
  • RLP - The radio link protocol used with L2R, including negotiated versions and reset behavior in Annex A.
  • IWF - The interworking function at the network side that exchanges data and control information with the MT during call establishment and data transfer.
  • Dm channel - The GSM signalling channel used for the mappings between terminal control and GSM 04.08 procedures.

Who uses SIST ETS 300 914 E3:2003?

SIST ETS 300 914 E3:2003 is used by GSM equipment designers, terminal adaptation implementers, and test engineers who need asynchronous data services to work across a GSM MT. It is also relevant to manufacturers of mobile terminals, data terminals, and adapter hardware that must present V.24, I.420, IrDA or PC Card style behavior.

Network and system engineers use it when implementing call setup, alternate speech/data transitions, non-transparent data handling, PAD access, and L2R/RLP interworking. Buyers and quality managers use it to check that a product supports the required asynchronous bearer capabilities and the documented GSM mapping behavior.

Which standards are used with SIST ETS 300 914 E3:2003?

The document depends on and cross-references several GSM and ITU-T texts:

  • GSM 07.01 - gives the general TAF framework that this standard builds on.
  • GSM 04.02 - defines the access reference configuration used for the MT and terminal attachment.
  • GSM 04.21 - defines the rate adaptation and status-bit handling used over the MS-BSS interface.
  • GSM 04.08 - provides the layer 3 signalling mapped from terminal call-control behavior.
  • GSM 07.07 - provides the AT command set used as an alternative to V.25 ter call control.
  • GSM 02.02 - defines the bearer services and asynchronous data rates referred to by the MT-TE2 link.
  • GSM 09.05 - provides the PAD access coding used for Dedicated PAD services.
  • V.24, V.25 bis, V.25 ter, V.42, V.42bis, V.110, I.420, X.28 - provide the interchange circuits, auto call/answer procedures, error correction, compression, frame format and break handling that the GSM mappings rely on.

What does the SIST ETS 300 914 E3:2003 document contain?

The document contains the reference configuration, the TAF functions for transparent and non-transparent services, GSM 04.08 mapping rules, and Dedicated PAD support. It also contains practical mapping details for V.24 circuits, status bits, call setup commands and indications, and the behavior needed for manual and automatic call control.

Annex A contains the detailed L2RCOP procedure, including PDU structure, status octets, pointer octets, radio link control, data transfer, flow control and break handling. It also describes how L2R behaves when data compression is active and the compression state has to be reinitialized.

Table 2 gives the minimum set of interchange circuits, and Table 3 gives the minimum set of call setup commands and indications. Figure 1 shows the L2R sub-functions, while Figure 2 gives example L2RCOP PDUs for single-slot and multislot cases, which is useful for design review and protocol testing.

Annex B gives the 9 pin V.24 layout for an MT2 type. That is useful when checking compact device connectors or mapping a reduced pin-count interface to the required GSM functions.

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Frequently Asked Questions

SIST ETS 300 914 E3:2003 is a standard published by the Slovenian Institute for Standardization (SIST). Its full title is "Digital cellular telecommunications system (Phase 2+) (GSM); Terminal Adaptation Functions (TAF) for services using asynchronous bearer capabilities (GSM 07.02 version 5.3.1)". This standard covers: This ETS defines the interfaces and Terminal Adaptation Functions (TAF) integral to a Mobile Termination (MT) which enables the attachment of asynchronous terminals to a MT (see GSM 04.02 [4]). The general aspects of Terminal Adaptation Functions are contained in GSM 07.01 (ETS 300 913.

This ETS defines the interfaces and Terminal Adaptation Functions (TAF) integral to a Mobile Termination (MT) which enables the attachment of asynchronous terminals to a MT (see GSM 04.02 [4]). The general aspects of Terminal Adaptation Functions are contained in GSM 07.01 (ETS 300 913.

SIST ETS 300 914 E3:2003 is classified under the following ICS (International Classification for Standards) categories: 33.070.50 - Global System for Mobile Communication (GSM). The ICS classification helps identify the subject area and facilitates finding related standards.

SIST ETS 300 914 E3:2003 is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.

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2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Digital cellular telecommunications system (Phase 2+) (GSM); Terminal Adaptation Functions (TAF) for services using asynchronous bearer capabilities (GSM 07.02 version 5.3.1)33.070.50Globalni sistem za mobilno telekomunikacijo (GSM)Global System for Mobile Communication (GSM)ICS:Ta slovenski standard je istoveten z:ETS 300 914 Edition 3SIST ETS 300 914 E3:2003en01-december-2003SIST ETS 300 914 E3:2003SLOVENSKI
STANDARD
EUROPEANETS 300 914TELECOMMUNICATIONJanuary 1998STANDARDThird EditionSource: SMGReference: RE/SMG-040702QR2ICS:33.020Key words:Digital cellular telecommunications system, Global System for Mobile communications (GSM)GLOBAL SYSTEM
FOR MOBILE COMMUNICATIONSRDigital cellular telecommunications system (Phase 2+);Terminal Adaptation Functions (TAF)for services using asynchronous bearer capabilities(GSM 07.02 version 5.3.1)ETSIEuropean Telecommunications Standards InstituteETSI SecretariatPostal address: F-06921 Sophia Antipolis CEDEX - FRANCEOffice address: 650 Route des Lucioles - Sophia Antipolis - Valbonne - FRANCEX.400: c=fr, a=atlas, p=etsi, s=secretariat - Internet: secretariat@etsi.frTel.: +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 300 914 E3:2003

Page 2ETS 300 914 (GSM 07.02 version 5.3.1): January 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 Editing and Committee Support Dept." at the address shown on the title page.SIST ETS 300 914 E3:2003

Page 3ETS 300 914 (GSM 07.02 version 5.3.1): January 1998ContentsForeword.51Scope.71.1Normative references.71.3Abbreviations.92Reference Configuration.92.1Customer Access Configuration.92.2Terminal Adaptation Function (TAF).93Terminal Adaptation Functions for transparent services.93.1Rate Adaptation.93.1.1Rate Adaptation - V series.103.1.2Rate Adaptation - S Interface (I.420).103.2Interchange Circuit Signalling Mapping.103.2.1Multislot configurations.103.2.2Channel coding TCH/F14.4.103.3Interface Signal Levels.103.4Call Establishment Signalling Mapping.103.4.1Autocalling/answering.103.4.2S Interface (I.420) Signalling Mapping.113.4.3Call Establishment Manual Operation - Utilizing Alternate Speech/Data orSpeech Followed By Data Capabilities.113.4.4Call Establishment Manual Operation - Utilizing the Unrestricted DigitalCapability.114Terminal Adaptation Functions for non transparent services.114.1Data Structure.114.1.1Data Structure on S Interface.114.1.2Data Structure on R Interface.114.1.3Data Structure Provided by the L2R Function to the RLP Function.114.2Signalling Mapping.114.3Flow Control.124.3.1Conditions Requiring Flow Control towards the Network.124.3.2Conditions Requiring Flow Control towards TE2.124.3.3Local Flow Control.124.3.4Character Orientated Protocol with No Flow Control.134.4Buffers.134.4.1TX Buffers.134.4.2RX Buffers.134.5Bit Transparency.134.6Transportation of "BREAK" condition.134.7Data Compression.135Terminal interfacing to GSM 04.08 Mapping.155.1Mobile Originated Calls.165.2Mobile Terminated Calls.166Functionality for the Support of Dedicated PAD Services.17Annex A (Normative):L2R Functionality.18A.1Introduction.18A.2The L2RCOP.18SIST ETS 300 914 E3:2003

Page 4ETS 300 914 (GSM 07.02 version 5.3.1): January 1998A.3Use of the L2RCOP.21A.3.1Radio Link Connection Control.21A.3.2Data Transfer.21A.3.3Status Transfer.21A.3.4Flow Control.21A.3.5Break.21A.3.5.1Normal Realization.21A.3.5.2Realization in case of Data Compression is used.21Annex B (Informative):Use of the 9 pin version of V.24 as a MT2 type.23History.24SIST ETS 300 914 E3:2003

Page 5ETS 300 914 (GSM 07.02 version 5.3.1): January 1998ForewordThis European Telecommunications Standard (ETS) has been produced by the Special Mobile Group(SMG) of the European Telecommunications Standards Institute (ETSI).This ETS defines the interfaces and Terminal Adaptation Functions (TAF) integral to a Mobile Termination(MT) which enables the attachment of asynchronous terminals to a MT within the digital cellulartelecommunications system (Phase 2+).The contents of this ETS is subject to continuing work within SMG and may change following formal SMGapproval. Should SMG modify the contents of this ETS, it will be resubmitted for OAP by ETSI with anidentifying 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.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 drafting rules.Transposition datesDate of adoption of this ETS:2 January 1998Date of latest announcement of this ETS (doa):30 April 1998Date of latest publication of new National Standardor endorsement of this ETS (dop/e):31 October 1998Date of withdrawal of any conflicting National Standard (dow):31 October 1998SIST ETS 300 914 E3:2003

Page 6ETS 300 914 (GSM 07.02 version 5.3.1): January 1998Blank pageSIST ETS 300 914 E3:2003

Page 7ETS 300 914 (GSM 07.02 version 5.3.1): January 19981ScopeThis European Telecommunications Standard (ETS) defines the interfaces and Terminal AdaptationFunctions (TAF) integral to a Mobile Termination (MT) which enables the attachment of asynchronousterminals to a MT (see GSM 04.02 [4]). The general aspects of Terminal Adaptation Functions arecontained in GSM 07.01 (ETS 300 913) [7]. This ETS covers support of these services for the followinginterfaces and procedures:(i)V.14 procedures(ii)V.21 DTE/DCE interface(iii)V.22bis DTE/DCE interface(iv)V.23 DTE/DCE interface(v)V.32 DTE/DCE procedures(vi)I.420 S interface(vii)V.25bis signalling procedures(viii)V.25ter signalling proceduresThe asynchronous data rates between the MT and the TE2 are defined in GSM 02.02 (ETS 300 904) [2].1.1Normative 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]GSM 01.04 (ETR 350): "Digital cellular telecommunication system (Phase 2+);Abbreviations and acronyms".[2]GSM 02.02 (ETS 300 904): "Digital cellular telecommunication system(Phase 2+); Bearer Services (BS) supported by a GSM Public Land MobileNetwork (PLMN)".[3]GSM 03.10: "Digital cellular telecommunication system (Phase 2+); GSM PublicLand Mobile Network (PLMN) connection types".[4]GSM 04.02: "Digital cellular telecommunication system (Phase 2+); GSM PublicLand Mobile Network (PLMN) access reference configuration".[5]GSM 04.08 (ETS 300 940): "Digital cellular telecommunication system(Phase 2+); Mobile radio interface layer 3 specification".[6]GSM 04.21 (ETS 300 945): "Digital cellular telecommunication system; Rateadaption on the Mobile Station - Base Station System (MS - BSS) interface ".[7]GSM 07.01 (ETS 300 913): "Digital cellular telecommunication system(Phase 2+); General on Terminal Adaptation Functions (TAF) for MobileStations (MS)".[8]GSM 07.07 (ETS 300 916): "Digital cellular telecommunication system(Phase 2+); AT command set for GSM Mobile Equipment (ME)[9]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 (PAD) facility access".[10]CCITT Recommendation V.4: "General structure of signals of internationalalphabet No.5 code for character oriented data transmission over publictelephone networks".SIST ETS 300 914 E3:2003

Page 8ETS 300 914 (GSM 07.02 version 5.3.1): January 1998[11]CCITT Recommendation V.25 bis (1988): Blue book, Volume VIII, FascicleVIII.1 "Automatic Calling and/or Answering Equipment on the General SwitchedTelephone Network (GSTN) using the 100-Series Interchange Circuits". [12]ITU-T Recommendation V.25 ter: "Serial asynchronous automatic dialling andcontrol".[13]CCITT Recommendation V.110: "Support of data terminal equipments (DTEs)with V-Series interfaces by an integrated services digital network".[14]CCITT Recommendation V.24 (1988): Blue book, Volume VIII, Fascicle VIII.1"List of definitions for interchange circuits between data terminal equipment(DTE) and data circuit-terminating equipment".[15]CCITT Recommendation V.21 (1988): Blue book, Volume VIII, Fascicle VIII.1"300 bits per second duplex modem standardized for use in the generalswitched telephone network".[16]CCITT Recommendation V.14 (1988): Blue book, Volume VIII, Fascicle VIII.1"Transmission of start-stop characters over synchronous bearer channels".[17]CCITT Recommendation V.22bis (1988): Blue book, Volume VIII, Fascicle VIII.1"2400 bits per second duplex modem using the frequency division techniquestandardized for use on the general".[18]CCITT Recommendation V.23 (1988): Blue book, Volume VIII, Fascicle VIII.1"600/1200-baud modem standardized for use in the general switched telephonenetwork".[19]CCITT Recommendation V.32 (1988): Blue book, Volume VIII, Fascicle VIII.1 "Afamily of 2-wire, duplex modems operating at data signalling rates of up to9600 bit/s for use in the general switched telephone network and on leasedtelephone-type circuits".[20]CCITT Recommendation V.42 (1988): Blue book, Volume VIII, Fascicle VIII.1"error-correcting procedures for DCEs using asynchronous-to-synchronousconversion".[21]ITU-T Recommendation V.42 bis: "Data compression procedures for data circuitterminating equipment (DCE) using error correction procedures[22]CCITT Recommendation X.28: "DTE/DCE interface for a start-stop mode dataterminal equipment accessing the packet assembly/disassembly facility (PAD) ina public data network situated in the same country".[23]Recommendations I.310-I.470 (Study Group XVIII): Blue book, Volume III,Fascicle III.8, Overall network aspects and functions, ISDN user-networkinterfaces.[24]CCITT Recommendation I.420: Blue book, Volume III, Fascicle III.8 "Basicuser-network interface".[25]Personal Computer Memory Card Association: "PCMCIA 2.1 or PC-Card 3.0electrical specification or later revisions".[26]Infrared Data Association IrDA "IrPHY Physical layer signalling standard".[27]TIA-617: "Data Transmission Systems and Equipment - In-Band DCE Control".[28]GSM 02.34: "Digital cellular telecommunications system (Phase 2+); HighSpeed Circuit Switched Data (HSCSD) - Stage 1”SIST ETS 300 914 E3:2003

Page 9ETS 300 914 (GSM 07.02 version 5.3.1): January 1998[29]GSM 03.34 (TS 101 038): "Digital cellular telecommunications system(Phase 2+); High Speed Circuit Switched Data (HSCSD) - Stage 2 ServiceDescription”1.3AbbreviationsAbbreviations used in this ETS are listed in GSM 01.04 (ETR 350) [1].2Reference ConfigurationGSM 07.01 (ETS 300 913) [7] and GSM 04.02 [4] describe the basic reference configurations.2.1Customer Access ConfigurationThis configuration is as shown in figure 1 of GSM 04.02 [4]. This ETS specifically refers to the MobileTerminations (MTs) which support terminals of the type TE1 and TE2 with asynchronous capabilities. TheTAF is functionally a part of an MT1, MT2 or MT0 with an integral asynchronous data capability.2.2Terminal Adaptation Function (TAF)The TAF provides facilities to allow manual or automatic call control functions associated with alternatespeech/data, speech followed by data and circuit switched services. The following functions are alsoincluded:-Conversion of electrical, mechanical, functional and procedural characteristics of the V series andISDN type interfaces to those required by the PLMN-Bit rate adaptation of the V series data signalling rates and the ISDN 64 kbit/s to that provided in thePLMN-The mapping functions necessary to convert automatic calling and/or automatic answeringprocedures of recommendation V.25 bis or V.25 ter and parameters for asynchronous operation-The mapping functions necessary to convert S interface signalling to the PLMN Dm channelsignalling-Flow control (in some cases resulting in non-transparency of data as described in section 4.3)-Layer 2 Relaying (see annex A)-In-call modification function-Synchronization procedure, which means the task of synchronizing the entry to and the exit fromthe data transfer phase between two user terminals. This is described in GSM 07.01(ETS 300 913) [7]-Filtering of channel control information as described in GSM 07.01 (ETS 300 913) [7]-Terminal compatibility checking- Splitting and combining of the data flow in case of multislot data configurations3Terminal Adaptation Functions for transparent servicesGSM 03.10 [3] refers to the connection types supporting the transparent services.3.1Rate AdaptationGSM 04.21 (ETS 300 945) [6] describes the rate adaptation scheme to be utilized over the Base Station(BS) to Mobile Station (MS) link. GSM 03.10 [3] refers to the rate adaptation elements to be provided inthe MS.SIST ETS 300 914 E3:2003

Page 10ETS 300 914 (GSM 07.02 version 5.3.1): January 19983.1.1Rate Adaptation - V seriesThis is provided as indicated in GSM 04.21 (ETS 300 945) [6].3.1.2Rate Adaptation - S Interface (I.420)The ISDN rate adapted frame format is modified to the PLMN rate adapted format as indicated inGSM 04.21 (ETS 300 945) [6].3.2Interchange Circuit Signalling MappingThe interchange circuit signalling mapping at the interface between the TE2 and the MT shall conform toCCITT Recommendation V.24 [14]. The signals required at this interface are shown in table 2.GSM 04.21 (ETS 300 945) [6] refers to the frame structure and identifies the use of the status bits for thecarriage of signalling information.Status bits (S1,S3,S4,S6,S8,S9 and X):The bits S and X are used to convey channel control information associated with the data bits in the datatransfer stage as shown below. The S bits are put into two groups SA and SB to carry the condition of twointerchange circuits. The X bit is used to carry the condition of circuit 106.The mechanism for proper assignment of the control information from the transmitting signal rate adapterinterface via these bits to the receiving signal rate adapter interface is shown below in table 1.For the S and X bits, a ZERO corresponds with the ON condition, a ONE with the OFF condition.108S1,S3,S6,S8 = SA107105S4,S9 = SB109106X106TE --- > IWFIWF ---- > TE3.2.1 Multislot configurationsIn transparent multislot configurations status bits S1, S3 and the X-bit between the D12 and D13 - in theITU-T V.110 80-bit intermediate rate frame - are used for transferring substream numbering information.The S4-bit is used for frame synchronization between the parallel substreams (ref GSM 04.21).3.2.2 Channel coding TCH/F14.4For information on the mapping of the interchange circuit signalling bits as specified
in GSM 04.21.3.3Interface Signal LevelsThe signal levels at the interface between the TE2 and the MT shall conform to CCITT V.28, or to IrDAIrPHY physical signalling standard specification, or to PCMCIA 2.1, or to PC-Card 3.0 electricalspecification or to later revisions.3.4Call Establishment Signalling Mapping3.4.1Autocalling/answeringThe mapping of the V.25 bis [11] procedures to the messages of the PLMN signalling in GSM 04.08(ETS 300 940) [5] is defined in section 5.a)Auto CallingThis procedure is provided according to V.25 bis [11] using only 108/2.SIST ETS 300 914 E3:2003

Page 11ETS 300 914 (GSM 07.02 version 5.3.1): January 1998A subset of V.25 bis is shown in table 3. This subset gives minimum level of control and indication.During the call establishment phase, i.e. after signalling, call tone according to V.25 bis shall begenerated in the IWF.An alternative to CCITT V.25bis [11] is to use the ITU-T V.25 ter dial command as specified inGSM 07.07 (ETS 300 916) [8].b)Auto AnswerThis procedure is provided according to V.25bis [11] or to V.25 ter [12].3.4.2S Interface (I.420) Signalling MappingThe mapping of Q.931 signalling to GSM 04.08 (ETS 300 940) [5] signalling requires the inclusion, by theMT, of PLMN specific elements (e.g. transparent or not, half/full rate
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