SIST ETS 300 914 E5:2003

Digital cellular telecommunications system (Phase 2+) (GSM); Terminal Adaptation Functions (TAF) for services using asynchronous bearer capabilities (GSM 07.02 version 5.5.1)

SUBJECT Clarification to L2R

Digitalni celični telekomunikacijski sistem (faza 2+) – Terminalske prilagajalne funkcije (TAF) za storitve, ki uporabljajo asinhrone nosilne zmogljivosti (GSM 07.02, različica 5.5.1)

General Information

• Status: Published
• Publication Date: 30-Nov-2003
• ICS: 33.070.50 - Global System for Mobile Communication (GSM)
• 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 300 914 ed.5 (1998-07) - Digital cellular telecommunications system (Phase 2+) (GSM); Terminal Adaptation Functions (TAF) for services using asynchronous bearer capabilities (GSM 07.02 version 5.5.1)

Standards Content (Sample)

SLOVENSKI STANDARD
SIST ETS 300 914 E5:2003
01-december-2003
'LJLWDOQLFHOLþQLWHOHNRPXQLNDFLMVNLVLVWHPID]D±7HUPLQDOVNHSULODJDMDOQH
IXQNFLMH7$)]DVWRULWYHNLXSRUDEOMDMRDVLQKURQHQRVLOQH]PRJOMLYRVWL*60
UD]OLþLFD
Digital cellular telecommunications system (Phase 2+) (GSM); Terminal Adaptation
Functions (TAF) for services using asynchronous bearer capabilities (GSM 07.02 version
5.5.1)
Ta slovenski standard je istoveten z: ETS 300 914 Edition 5
ICS:
33.070.50 Globalni sistem za mobilno Global System for Mobile
telekomunikacijo (GSM) Communication (GSM)
SIST ETS 300 914 E5:2003 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST ETS 300 914 E5:2003

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SIST ETS 300 914 E5:2003
EUROPEAN ETS 300 914
TELECOMMUNICATION July 1998
STANDARD Fifth Edition
Source: SMG Reference: RE/SMG-040702QR4
ICS: 33.020
Key words: Digital cellular telecommunications system, Global System for Mobile communications (GSM)
R
GLOBAL SYSTEM FOR
MOBILE COMMUNICATIONS
Digital cellular telecommunications system (Phase 2+);
Terminal Adaptation Functions (TAF)
for services using asynchronous bearer capabilities
(GSM 07.02 version 5.5.1)
ETSI
European Telecommunications Standards Institute
ETSI Secretariat
Postal address: F-06921 Sophia Antipolis CEDEX - FRANCE
Office address: 650 Route des Lucioles - Sophia Antipolis - Valbonne - FRANCE
Internet: [e-mail] - http://www.etsi.fr - http://www.etsi.org
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 1998. All rights reserved.

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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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Contents
Foreword .5
1 Scope .7
1.1 Normative references .7
1.3 Abbreviations .9
2 Reference Configuration .9
2.1 Customer Access Configuration .9
2.2 Terminal Adaptation Function (TAF).9
3 Terminal Adaptation Functions for transparent services.9
3.1 Rate Adaptation .9
3.1.1 Rate Adaptation - V series .10
3.1.2 Rate Adaptation - S Interface (I.420).10
3.2 Interchange Circuit Signalling Mapping .10
3.2.1 Multislot configurations (TCH/F9.6 or TCH/F4.8).10
3.2.2 Channel coding TCH/F14.4.10
3.3 Interface Signal Levels.10
3.4 Call Establishment Signalling Mapping.11
3.4.1 Autocalling/answering.11
3.4.2 S Interface (I.420) Signalling Mapping .11
3.4.3 Call Establishment Manual Operation - Utilizing Alternate Speech/Data or
Speech Followed By Data Capabilities.11
3.4.4 Call Establishment Manual Operation - Utilizing the Unrestricted Digital
Capability.11
4 Terminal Adaptation Functions for non transparent services.11
4.1 Data Structure.11
4.1.1 Data Structure on S Interface.11
4.1.2 Data Structure on R Interface.11
4.1.3 Data Structure Provided by the L2R Function to the RLP Function .12
4.2 Signalling Mapping.12
4.3 Flow Control.12
4.3.1 Conditions Requiring Flow Control towards the Network .12
4.3.2 Conditions Requiring Flow Control towards TE2.12
4.3.3 Local Flow Control.12
4.3.4 Character Orientated Protocol with No Flow Control .13
4.4 Buffers .13
4.4.1 TX Buffers .13
4.4.2 RX Buffers.13
4.5 Bit Transparency.13
4.6 Transportation of "BREAK" condition.13
4.7 Data Compression .13
5 Terminal interfacing to GSM 04.08 Mapping.15
5.1 Mobile Originated Calls.16
5.2 Mobile Terminated Calls .16
6 Functionality for the Support of Dedicated PAD Services.17
Annex A (Normative): L2R Functionality.18
A.1 Introduction.18
A.2 The L2RCOP.18

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A.3 Use of the L2RCOP. 21
A.3.1 Radio Link Connection Control. 21
A.3.2 Data Transfer . 21
A.3.3 Status Transfer. 21
A.3.4 Flow Control . 21
A.3.5 Break. 21
A.3.5.1 Normal Realization . 21
A.3.5.2 Realization in case of Data Compression is used . 21
Annex B (Informative): Use of the 9 pin version of V.24 as a MT2 type. 23
History. 24

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Foreword
This 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 cellular
telecommunications system (Phase 2+).
The contents of this ETS is subject to continuing work within SMG and may change following formal SMG
approval. Should SMG modify the contents of this ETS, it will be resubmitted for OAP by ETSI with an
identifying change of release date and an increase in version number as follows:
Version 5.x.y
where:
y the third digit is incremented when editorial only changes have been incorporated in the
specification;
x the 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 dates
Date of adoption of this ETS: 19 June 1998
Date of latest announcement of this ETS (doa): 31 October 1998
Date of latest publication of new National Standard
or endorsement of this ETS (dop/e): 30 April 1999
Date of withdrawal of any conflicting National Standard (dow): 30 April 1999

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1 Scope
This European Telecommunications Standard (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) [7]. This ETS covers support of these services for the following
interfaces 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 procedures
The asynchronous data rates between the MT and the TE2 are defined in GSM 02.02 (ETS 300 904) [2].
1.1 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] 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 Mobile
Network (PLMN)".
[3] GSM 03.10: "Digital cellular telecommunication system (Phase 2+); GSM Public
Land Mobile Network (PLMN) connection types".
[4] GSM 04.02: "Digital cellular telecommunication system (Phase 2+); GSM Public
Land 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; Rate
adaption 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 Mobile
Stations (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 between
the Public Land Mobile Network (PLMN) and the Packet Switched Public Data
Network (PSPDN) for Packet Assembly/Disassembly (PAD) facility access".
[10] CCITT Recommendation V.4: "General structure of signals of international
alphabet No.5 code for character oriented data transmission over public
telephone networks".

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[11] CCITT Recommendation V.25 bis (1988): Blue book, Volume VIII, Fascicle
VIII.1 "Automatic Calling and/or Answering Equipment on the General Switched
Telephone Network (GSTN) using the 100-Series Interchange Circuits".
[12] ITU-T Recommendation V.25 ter: "Serial asynchronous automatic dialling and
control".
[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 general
switched 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 technique
standardized 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 telephone
network".
[19] CCITT Recommendation V.32 (1988): Blue book, Volume VIII, Fascicle VIII.1 "A
family of 2-wire, duplex modems operating at data signalling rates of up to
9600 bit/s for use in the general switched telephone network and on leased
telephone-type circuits".
[20] CCITT Recommendation V.42 (1988): Blue book, Volume VIII, Fascicle VIII.1
"error-correcting procedures for DCEs using asynchronous-to-synchronous
conversion".
[21] ITU-T Recommendation V.42 bis: "Data compression procedures for data circuit
terminating equipment (DCE) using error correction procedures
[22] CCITT Recommendation X.28: "DTE/DCE interface for a start-stop mode data
terminal equipment accessing the packet assembly/disassembly facility (PAD) in
a 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-network
interfaces.
[24] CCITT Recommendation I.420: Blue book, Volume III, Fascicle III.8 "Basic
user-network interface".
[25] Personal Computer Memory Card Association: "PCMCIA 2.1 or PC-Card 3.0
electrical 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+); High
Speed Circuit Switched Data (HSCSD) - Stage 1”

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[29] GSM 03.34 (TS 101 038): "Digital cellular telecommunications system
(Phase 2+); High Speed Circuit Switched Data (HSCSD) - Stage 2 Service
Description”
1.3 Abbreviations
Abbreviations used in this ETS are listed in GSM 01.04 (ETR 350) [1].
2 Reference Configuration
GSM 07.01 (ETS 300 913) [7] and GSM 04.02 [4] describe the basic reference configurations.
2.1 Customer Access Configuration
This configuration is as shown in figure 1 of GSM 04.02 [4]. This ETS specifically refers to the Mobile
Terminations (MTs) which support terminals of the type TE1 and TE2 with asynchronous capabilities. The
TAF is functionally a part of an MT1, MT2 or MT0 with an integral asynchronous data capability.
2.2 Terminal Adaptation Function (TAF)
The TAF provides facilities to allow manual or automatic call control functions associated with alternate
speech/data, speech followed by data and circuit switched services. The following functions are also
included:
- Conversion of electrical, mechanical, functional and procedural characteristics of the V series and
ISDN 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 the
PLMN.
- The mapping functions necessary to convert automatic calling and/or automatic answering
procedures 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 channel
signalling.
- Flow control (in some cases resulting in non-transparency of data as described in subclause 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 from
the 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 configurations.
3 Terminal Adaptation Functions for transparent services
GSM 03.10 [3] refers to the connection types supporting the transparent services.
3.1 Rate Adaptation
GSM 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 in
the MS.

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3.1.1 Rate Adaptation - V series
This is provided as indicated in GSM 04.21 (ETS 300 945) [6].
3.1.2 Rate Adaptation - S Interface (I.420)
The ISDN rate adapted frame format is modified to the PLMN rate adapted format as indicated in
GSM 04.21 (ETS 300 945) [6].
3.2 Interchange Circuit Signalling Mapping
The interchange circuit signalling mapping at the interface between the TE2 and the MT shall conform to
CCITT 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 the
carriage 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 data
transfer stage as shown below. The S bits are put into two groups SA and SB to carry the condition of two
interchange 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 adapter
interface 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.
108 S1,S3,S6,S8 = SA 107
105 S4,S9 = SB 109
106 X 106
TE --- > IWF IWF ---- > TE
3.2.1 Multislot configurations (TCH/F9.6 or TCH/F4.8)
In transparent multislot configurations status bits S1, S3 and the X-bit between the D12 and D13 - in the
ITU-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/F14.4
For information on the mapping of the interchange circuit signalling bits in the 14,5 kbit/s multiframe
structure, refer to GSM 04.21.
3.3 Interface Signal Levels
The signal levels at the interface between the TE2 and the MT shall conform to CCITT V.28, or to IrDA
IrPHY physical signalling standard specification, or to PCMCIA 2.1, or to PC-Card 3.0 electrical
specification or to later revisions.

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3.4 Call Establishment Signalling Mapping
3.4.1 Autocalling/answering
The 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 Calling
This procedure is provided according to V.25 bis [11] using only 108/2.
A 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 be
generated in the IWF.
An alternative to CCITT V.25bis [11] is to use the ITU-T V.25 ter dial command as specified in
GSM 07.07 (ETS 300 916) [8].
b) Auto Answer
This procedure is provided according to V.25bis [11] or to V.25 ter [12].
3.4.2 S Interface (I.420) Signalling Mapping
The mapping of Q.931 signalling to GSM 04.08 (ETS 300 940) [5] signalling requires the inclusion, by the
MT, of PLMN specific elements (e.g. transparent or not, half/full rate channel). For asynchronous Bearer
services, requests for bearer capabilities not listed in table 4 (or where the "Users information layer 1
protocol" element does not indicate V.110) will result in call rejection.
3.4.3 Call Establishment Manual Operation - Utilizing Alternate Speech/Data or Speech
Followed By Data Capabilities
During manual call establishment, the mobile user shall be able to hear network supervisory tones and
answer tone.
On hearing answer tone, the user invokes the transition from speech to data in both the MS and the IWF.
The mapping for this is shown in section 5.
3.4.4 Call Establishment Manual Operation - Utilizing the Unrestricted Digital Capability
In this case the user will not hear network supervisory tones or answer tone. The data transfer phase will
be entered automatically.
4 Terminal Adaptation Functions for non transparent services
The V.24 interface shall provide inband (XON/XOFF) and out of band (CT106) flow control. The use of
CT133 for out of band flow control shall be implemented according to CCITT Recommendation V.42 [20].
4.1 Data Structure
4.1.1 Data Structure on S Interface
The protocol models for this are described in cases 3a and 3d of GSM 03.10. The data structure will be
according to CCITT V.110.
4.1.2 Data Structure on R Interface
The protocol models for this are described in cases 3b and 3e of GSM 03.10. The data will consist of 7 or
8 bit characters with additional start and stop elements. The 7 bit data can additionally have an associated
parity bit, 8 bit data cannot have an additional parity bit.

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4.1.3 Data Structure Provided by the L2R Function to the RLP Function
See annex A.
4.2 Signalling Mapping
This is identical to the transparent case with the exception of the transparent/non-transparent element,
see section 5.
In addition, the L2R/RLP will give an explicit indication when the link into the connected network is
established. If the link fails, an explicit "link lost" indication will be given. The mapping of these procedures
to the V.24 interface is defined in annex A.
4.3 Flow Control
The passage of flow control information between L2Rs is described in annex A. Subclauses 4.3.1, 4.3.2
and 4.3.3 describe the operation of the flow control mechanisms. These mechanisms apply for all the
non-transparent services covered by this specification, with the exception of Character Orientated Protocol
with No Flow Control which is treated in subclause 4.3.4.
4.3.1 Conditions Requiring Flow Control towards the Network
The L2R function will send immediately a "flow control active" indication in the following circumstances:
(i) If the receive buffer from the radio side reaches a preset threshold (BACKPRESSURE).
(ii) If local flow control is initiated by the TE2 (see subclause 4.3.3 a) or c)). On receipt of this flow
control indication transmission of data from the receive buffer towards the TE2 is halted.
On removal of the buffer congestion or local flow control the L2R will send a "flow control inactive"
indication.
In addition, for the local flow control condition, transmission of data from the receive buffers will be
restarted.
4.3.2 Conditions Requiring Flow Control towards TE2
The L2R functions will immediately activate local flow control (see subclause 4.3.3 b) or d)) under the
following circumstances:
(i) The transmit buffer reaches a pre-set threshold (BACKPRESSURE).
(ii) The L2R receives a "flow control active" indication.
On removal of buffer congestion or receipt of L2R/RLP "flow control inactive" the local flow control will be
removed.
4.3.3 Local Flow Control
Two methods of local flow control are allowed:
Outband
a) From TE2: CT133 shall be turned off to indicate flow control active, and on to indicate flow control
inactive.
b) From TAF: CT106 shall be turned off to indicate flow control active, and on to indicate flow control
inactive.
Inband

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c) From TE2: XOFF is sent to indicate flow control active. XON is sent to indicate flow control inactive.
The XON/XOFF characters are extended by the L2R from the data stream and are not sent across
the radio interface. Where XON/XOFF is utilized then the TAF will generate flow control
active/inactive immediately, i.e. the XON/XOFF characters do not enter the transmit buffer.
d) From TAF: As from TE2
If the outband method is used, the L2R will pass the DC1/DC3 characters as data, i.e. no flow control
indications will be generated on receipt of DC1/DC3.
4.3.4 Character Orientated Protocol with No Flow Control
If the users layer 2 indicates Character Orientated Protocol with no flow control then no flow control is
used i.e. the X-bit is not set and DC1/DC3 are passed through as data.
4.4 Buffers
4.4.1 TX Buffers
Data received on CT103 from the TE2 shall be buffered such that if the MT is unable to transfer the data
over the radio path then data is not lost.
The buffer shall be capable of holding the data. Its size is up to the implementors.
When the buffer is half full, TE2 shall be flow controlled as per subclause 4.3.2, unless Character
Orientated Protocol with No Flow Controlis being used (see subclause 4.3.4).
4.4.2 RX Buffers
Data for transfer to the TE2 on CT104 shall be buffered such that if the TE2 is unable to accept data then
data transferred from the MT is not lost.
The buffer size should be up to the implementors.
When the buffer becomes half full, the L2R will send a "flow control active" indication, unless Character
Orientated Protocol with No Flow Control is being used.
4.5 Bit Transparency
V.25bis indications generated by the TAF shall be even parity, even if the parity condition for the user's
application is different.
4.6 Transportation of "BREAK" condition
The "BREAK" condition must be recognized by the L2R function and passed immediately to the IWF. The
L2R will generate a "BREAK" condition to the TE2 on receipt of a "BREAK" indication from the IWF.
Annex A describes how the L2R will transport the "BREAK" indication.
4.7 Data Compression
L2R includes a data compression function according to ITU-T V.42bis that spans from the MS to the IWF
in the MSC. The error correction function is provided by RLP instead of ITU-T V.42. RLP XID is used to
negotiate compression parameters. L2R includes the V.42bis control function especially for reinitializing in
case of break recognition or RLP reset and error indication by the data compression function respectively.

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Table 2: Minimum set of Interchange Circu
...