ETSI ETS 300 931 ed.2 (1997-08)

SLOVENSKI STANDARD
SIST ETS 300 931 E2:2003
01-december-2003
'LJLWDOQLFHOLþQLWHOHNRPXQLNDFLMVNLVLVWHPID]D±7HKQLþQDL]YHGEDIDNVLPLOQH
VNXSLQHWUDQVSDUHQW*60UD]OLþLFD
Digital cellular telecommunications system (Phase 2+) (GSM); Technical realization of
facsimile group 3 transparent (GSM 03.45 version 5.1.1)
Ta slovenski standard je istoveten z: ETS 300 931 Edition 2
ICS:
33.070.50 Globalni sistem za mobilno Global System for Mobile
telekomunikacijo (GSM) Communication (GSM)
SIST ETS 300 931 E2:2003 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST ETS 300 931 E2:2003

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SIST ETS 300 931 E2:2003
EUROPEAN ETS 300 931
TELECOMMUNICATION August 1997
STANDARD Second Edition
Source: ETSI SMG Reference: RE/SMG-040345QR
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+);
Technical realization of facsimile group 3 transparent
(GSM 03.45 version 5.1.1)
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
X.400: c=fr, a=atlas, p=etsi, s=secretariat - Internet: secretariat@etsi.fr
Tel.: +33 4 92 94 42 00 - Fax: +33 4 93 65 47 16
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 1997. 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
0 Scope .7
0.1 Normative references .7
0.2 Definitions and abbreviations.8
1 Service definition .9
2 Network architecture .9
3 Reference configuration at the mobile station.10
3.1 Fax Adaptor functionality .10
3.2 GSM Facsimile Machine functionality.11
4 Connection types.12
4.1 Information transfer protocol model.13
4.2 Interactions with T.30.14
4.2.1 Link control strategy .14
4.2.1.1 Message detection.15
4.2.2 Speed conversion for BCS phases .15
4.2.3 Compatibility checking.16
4.2.3.1 Group 1 and Group 2 support.16
4.2.3.2 2 400 bit/s handshaking.16
4.2.3.3 Non-standard facilities .16
4.2.3.4 12 000 and 7 200 bit/s Facsimile Document Transfer.16
4.2.3.5 Procedure interrupts .16
4.2.4 Speed checking.16
4.3 Radio Channel Modification Procedures.17
4.3.1 In Call Modification (ICM) .17
4.3.2 Channel Mode Modify (CMM).18
5 Use of terminal adaptation functions.19
5.1 Standard TAFs for synchronous services.19
5.2 Specific TAFs for facsimile service.19
5.2.1 Working principle.19
5.2.2 Basic protocol structure.20
5.2.2.1 Frame formats .20
5.2.3 Protocol description.21
5.2.3.1 IDLE state.21
5.2.3.2 BCS-REC state.21
5.2.3.3 BCS-TRA state .21
5.2.3.4 MSG-REC state.22
5.2.3.5 MSG-TRA state .22
5.2.4 DCS and TCF processing .23
5.2.5 DCN (disconnect) frame.23
5.2.6 Clocking.23
5.2.7 Time-outs .24
5.3 Specific TAFs for facsimile service (T.30/A).24
5.3.1 Frame detection .24
5.3.2 Message phase.24
5.3.3 Additional CMM request .24
6 Signalling aspects .25
6.1 Handling of Tonal Signals.25
6.2 Call establishment.25
6.2.1 Mobile Terminated Call - Speech then Fax.25
6.2.2 Mobile Terminated Call - Auto answer .26

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6.2.3 Mobile Originated Call - Speech then Fax . 26
6.2.4 Mobile Originated Call - Auto calling. 27
6.2.5 Mobile Originated Call - Manual calling . 27
6.3 Call release . 27
7 Interworking to fixed networks . 27
7.1 Interworking to PSTN . 28
7.2 Interworking to ISDN .28
Annex I (informative): Protocol entities from CCITT T.30 and T.4. 29
Annex II (informative): Procedure examples. 30
History. 43

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Foreword
This European Telecommunication Standard (ETS) has been produced by the Special Mobile Group
(SMG) of the European Telecommunications Standards Institute (ETSI).
This ETS defines the technical realization of facsimile group 3 using transparent network support within
the digital cellular telecommunications system.
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.
Transposition dates
Date of adoption: 8 August 1997
Date of latest announcement of this ETS (doa): 30 November 1997
Date of latest publication of new National Standard
or endorsement of this ETS (dop/e): 31 May 1998
Date of withdrawal of any conflicting National Standard (dow): 31 May 1998

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0 Scope
This European Telecommunication Standard (ETS) deals with the procedures allowing the technical
realization of the Group 3 facsimile Service within the GSM PLMN using transparent Network support,
according to the definition of Teleservice 61 and 62 specified in the GSM 02.03 [2].
0.1 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 telecommunications system (Phase 2+):
Abbreviations and acronyms".
[2] GSM 02.03 (ETS 300 905): "Digital cellular telecommunications system
(Phase 2+); Teleservices supported by a GSM Public Land Mobile Network
(PLMN)".
[3] GSM 02.34: "Digital cellular telecommunications system (Phase 2+): High
Speed Circuit Switched Data (HSCSD) - Stage 1".
[4] GSM 03.10: "Digital cellular telecommunications system (Phase 2+); GSM
Public Land Mobile Network (PLMN) connection types".
[5] GSM 03.34 (TS 101 038): "Digital cellular telecommunications system
(Phase 2+); High Speed Circuit Switched Data (HSCSD) - Stage 2".
[6] GSM 04.02: "Digital cellular telecommunications system (Phase 2+); GSM
Public Land Mobile Network (PLMN) access reference configuration".
[7] GSM 04.08 (ETS 300 940): "Digital cellular telecommunications system
(Phase 2+); Mobile radio interface layer 3 specification".
[8] GSM 04.21 (ETS 300 945): "Digital cellular telecommunications system; Rate
adaption on the Mobile Station - Base Station System (MS - BSS) interface".
[9] GSM 07.01 (ETS 300 913): "Digital cellular telecommunications system
(Phase 2+); General on Terminal Adaptation Functions (TAF) for Mobile
Stations (MS)".
[10] GSM 07.03 (ETS 300 915): "Digital cellular telecommunications system
(Phase 2+); Terminal Adaptation Functions (TAF) for services using
synchronous bearer capabilities".
[11] GSM 09.07 (ETS 300 976): "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)".
[12] CCITT Recommendation T.35: "Procedure for the allocation of CCITT
members' codes".
[13] CCITT Recommendation F.160 Fascicle II.5: "General operational provision for
the international public facsimile".
[14] CCITT Recommendation T.4 Fascicle VII.3: "Standardization of group 3
facsimile apparatus for document transmission".

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[15] CCITT Recommendation T.30 Fascicle VII.3: "Procedures for document
facsimile transmission in the general switched telephone network".
[16] CCITT Recommendation V.21 Fascicle VIII.l: "300 bits per second duplex
modem standardized for use in the general switched telephone network".
[17] CCITT Recommendation V.24 Fascicle VIII.l: "List of definitions for interchange
circuits between Data Terminal Equipment (DTE) and Data Circuit-terminating
Equipment (DCE)".
[18] CCITT Recommendation V.25bis Fascicle VIII.l: "Automatic calling and/or
answering equipment on the General Switched Telephone Network (GSTN)
using the 100-series interchange circuits".
[19] CCITT Recommendation V.27ter Fascicle VIII.l: "4 800/2 400 bits per second
modem standardized for use in the general switched telephone network".
[20] CCITT Recommendation V.29 Fascicle VIII.l: "9 600 bits per second modem
standardized for use on point-to-point 4-wire leased telephone-type circuits".
[21] CCITT Recommendation V.33 Fascicle VIII.l: "14 400 bits per second modem
standardized for use on point-to-point 4-wire leased telephone-type circuits".
[22] CCITT Recommendation X.300 Fascicle VIII.6: "General principles for
interworking between public networks, and between public networks and other
networks for the provision of data transmission services".
[23] CCITT Recommendation V.17: "A 2-wire modem for facsimile applications with
rates up to 14 400 bit/s".
0.2 Definitions and abbreviations
In addition to those below, abbreviations used in this ETS are listed in GSM 01.04 [1].
BCS Binary Coded Signalling phase of Facsimile transmission as per CCITT T.30
CT105 Interchange Circuit 105 as per CCITT V.24
CT106 Interchange Circuit 106 as per CCITT V.24
CT107 Interchange Circuit 107 as per CCITT V.24
CT108.2 Interchange Circuit 108/2 as per CCITT V.24
CT109 Interchange Circuit 109 as per CCITT V.24
CT114 Interchange Circuit 114 as per CCITT V.24
CT115 Interchange Circuit 115 as per CCITT V.24
FA/MT The Fax Adaptor specifically located at MT side
FA/IWF The Fax Adaptor specifically located at IWF side
MSG Message phase of Facsimile transmission as per CCITT T.30
All protocol entities from CCITT Facsimile Recommendations (T.4 and T.30) apply; in this ETS they are
referenced to in the same way as in the above CCITT Recommendations (see also annex I to this ETS).

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1 Service definition
The fixed network Group 3 Facsimile service, as basically defined in CCITT Recommendation F.160, is an
international telematic service for ISO A4 document transmission between two facsimile stations.
The service specification is comprised of two parts: the control protocol described in CCITT
Recommendation T.30, and the document transmission coding described in CCITT Recommendation T.4.
The GSM facsimile Teleservice is intended to allow facsimile connections between group 3 apparatus
using:
- a GSM PLMN as a stand alone facility, for mobile to mobile communication;
- a GSM PLMN to gain access to fixed networks PSTN and ISDN, for mobile to/from land
communication.
For this Teleservice, the document coding is as CCITT Recommendation T.4 with no modifications. The
protocol used is CCITT Recommendation T.30 modified within the PLMN as detailed in this ETS.
The interworking between different networks is based on CCITT Recommendation X.300.
The particular features of this Teleservice are:
- it uses point-point communication;
- the information transfer capability is dual "Speech"/"Group 3 Facsimile" for Teleservice 61 and
"Group 3 Facsimile" only for Teleservice 62;
- both mobile originated and terminated calls are supported;
- the information transfer mode is circuit, duplex, synchronous and symmetric;
- different end-to-end transfer rates are used within the same call to take advantage of the better
radio path error rate;
- use of a standard synchronous terminal adaptation function (as per GSM 07.03) within the MS.
2 Network architecture
The network architecture applicable to this Teleservice is shown in figure 1/03.45, below.
PLMN
v v
PSTN FAX
FAX BSS MSC/IWF
MT
ISDN
Figure 1/03.45: Network architecture
This shows the case of mobile to fixed network interworking. For mobile to mobile calls, there would
effectively be a loop back within the PLMN, using two IWFs.

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3 Reference configuration at the mobile station
The mobile reference configurations described in this clause are defined as per GSM 04.02.
 Mobile Station
R U
2w
m
FAX
a)
FAX /
MT2
Adapt.
S
2w
FAX
b)
FAX /
MT1
TA
Adapt.
2w
FAX
/
c) FAX TA MT1
Adapt.
R
d) FAX
FAX
MT2
Adapt.
FAX
e)
FAX TA
MT1
Adapt.
f)
MT0
Figure 2/03.45: Reference configurations
The Teleservice definition in GSM 02.03 regards the group 3 facsimile terminal as a 2-wire analogue
terminated equipment. In order to connect this to the MT2 a separate "Fax Adaptor" device is necessary.
This configuration, shown in figure 2a/03.45, has to be considered as the standard configuration, so that
all the existing Group 3 facsimile apparatus can be connected to the PLMN.
An alternative realization would be to combine a standard group 3 facsimile machine and the Fax Adaptor
into a specially developed "GSM facsimile machine", directly providing a digital output. Although such a
device must appear to the MT2 as identical to the Fax Adaptor (i.e. with an identical interface and
protocol), it would allow for a significantly smaller and simpler facsimile machine. This configuration is
shown in figure 2d/03.45 and is regarded as a desirable alternative.
In addition of course, it is always possible to realize an MT0, as per figure 2f/03.45, where both the
facsimile and mobile termination functions are considered to be part of one integrated unit.
The remaining configurations concern the use of an S interface and are considered as optional
configurations. Their use is for further study.
The particular terminal adaptation functions used are those detailed in GSM 07.03 and the interface to the
MT2 used is synchronous V.24 with an option for support of V.25bis procedures for autocalling and
autoanswering.
3.1 Fax Adaptor functionality
The Fax Adaptor block, figure 3/03.45, is intended to specifically complement the Group 3 facsimile
apparatus in order to be able to communicate over a GSM PLMN.

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COMPOSITE
  MODEM
R
2W
PROTOCOL
MONITORING
    &
CONTROL
TONE
HANDLING
Figure 3/03.45: Fax Adaptor scheme
Whether it has to be a function internal to the GSM PLMN, or an external accessory associated with the
Group 3 apparatus, is beyond the scope of this ETS, and in any case, does not affect at all the working of
the procedure as here described.
It can be functionally partitioned in two clauses:
- an analogue clause, dealing with:
- the modulation and demodulation processes according to CCITT Recommendation V.21,
V.27ter, V.29 and V.17 as explained in T.4 and T.30;
- handling of the signalling on the 2-wire path to the facsimile machine, including autocalling
and autoanswer functions where necessary (see clause 6).
- a digital clause, dealing with:
- monitoring and where necessary, manipulation of the T.30 protocol as detailed in the rest of
this ETS;
- overall control of the adaptor;
- connection over the synchronous V.24 interface to the MT as described in GSM 07.03;
- where necessary, autocalling and autoanswering functions according to V.25bis.
In the following this specification will reference the Fax Adaptor functionality, considering the most general
case where it operates as a full-featured (see figure 3/03.45) separate block (see figure 2a/03.45), as this
reference configuration is implicitly or explicitly exhaustive of all service related technical aspects.
3.2 GSM Facsimile Machine functionality
The special GSM facsimile machine shown in the MS configuration of figure 2d/03.45 has a similar
functionality to the digital part of the Fax Adaptor, but without any of the analogue portions.
It appears over the V.24 interface as identical to the Fax Adaptor, i.e. the MT2 needs to have no
knowledge of the particular configuration used.
When necessary this reference configuration, will be explicitly referenced to in the following; otherwise all
technical aspects relevant to the configuration implicitly apply.

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4 Connection types
Table 1/03.45 shows the connection elements attributes applicable to this Teleservice (note), adapted
from GSM 03.10.
NOTE 1: Teleservice 61 includes both speech and data connection types, but Teleservice 62
only the data connection type.
Table 1/03.45: Elements of connection types
Protocol type Access to TAF Radio interface Intermediate BS-MSC/IWF
of figure 6 of TS of the Mobile connection rate connection
GSM 03.10 Station element RA1 to RA2 element
Model 6: Speech - Speech/GSM - CCITT
A-law
Model 5: C/D/S UDI C/D/S UDI
C/D/S UDI C/D/S UDI
Facsimile - 9.6 kbit/s - 12.0 kbit/s - 16 kbit/s - 64 kbit/s
Group 3 - 4.8 kbit/s - 6.0 kbit/s -  8 kbit/s - 64 kbit/s
- 2.4 kbit/s - 3.6 kbit/s -  8 kbit/s - 64 kbit/s
(note)
Model 5b C/D/S UDI C/D/S UDI C/D/S UDI C/D/S UDI
Facsimile - 14.4 kbit/s 2X12 kbit/s 2X16 kbit/s - 64 kbit/s
Group 3 -  9.6 kbit/s 12 or 2X6 kbit/s 16 or 2X8 kbits - 64 kbit/s
-  4.8 kbit/s 6 kbit/s 8 kbit/s - 64 kbit/s
-  2.4 kbit/s 6 kbits 8 kbit/s - 64 kbit/s
NOTE 2: The highest Access Rate actually supported in this teleservice will be consistent with
the highest Access Rate of the Transparent Bearer Service provided by the Network
Operator.
C = Circuit switched S = Synchronous
D = Full-duplex UDI = Unrestricted Digital Information
Table 1a/03.45
Fax modem rates No. of Radio i/f rate Intermediate Rate Padding Scheme
substreams
14.4 kbit/s 2 12 kbit/s 16 kbit/s P
12.0 kbit/s 2 12 kbit/s 16 kbit/s FA,5D + S
9.6 kbit/s 1 12 kbit/s 16 kbit/s
2 6 kbit/s 8 kbit/s
7.2 kbit/s 1 12 kbit/s 16 kbit/s FA,3D + S
2 6 kbit/s 8 kbit/s FA,3D + S
4.8 kbit/s (note1) 1 6 kbit/s 8 kbit/s
2.4 kbit/s 1 6 kbit/s 8 kbit/s
NOTE 3: For multislot operations the number of channels is downgraded by releasing one
channel when the facsimile rate drops from 7.2 kbit/s to 4.8 kbit/s. However it shall not
be possible to upgrade the number of channels in either multislot or single slot
configurations.
P = Padding is performed in V.110 as specified in GSM TS 04.21.
FA = Padding is performed in the FA.
nD + mS = m SYNC frames will be added every n'th DATA frame.
The figure 4/03.45 shows the scheme of a typical GSM PLMN connection for this Teleservice, considering
respectively R and S access at Network Termination.
To grant full support to the CCITT Recommendation T.30, requiring different transmission speeds, the
following strategy shall be implemented:

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- PLMN provides for four Access Rates only, that is 14 400 bits/s, 9 600 bit/s, 4 800 bit/s, 2 400 bit/s;
- radio channel modification procedures are used for switching between Speech phase and facsimile
phase, as well as to select the suitable Access Rate (14 400, 9 600/4 800/2 400 bit/s) within the
facsimile phase, as resulting from the preliminary end-to-end negotiation between the terminals;
- to transport Binary Coded Signalling (BCS) requiring a synchronous 300 bit/s bit-rate, speed
conversion will be used at both the PLMN ends.
DTE DCE
MT2
MSC/IWF
3.1 kHz audio
P
2w
FAX
FAX 2w
L
Adaptor
R I/F M Adaptor
(V.24)
N
MT1
MSC/IWF
3.1 kHz audio
FAX
P
2w
2w
L
Adaptor
M
S I/F
N
Figure 4b/03.45: Optional Teleservice connection (F.F.S)
4.1 Information transfer protocol model
The figure 5/03.45 depicts the conceptual protocol model for this Teleservice, deduced from model 5 and
5b of figure 6/03.10.
The main point to be underlined is that all the protocol modules specific for this Teleservice are confined in
the Fax Adaptation functions at both the MT and IWF ends. Note that model 5b of figure 6/03.10 details
the placing of the splitting and combiner function for multislot configurations.
GR 3 Apparatus
GR 3 Apparatus
FAX
Adaptor
TA
G R 3 Apparatus
GR 3 Apparatus

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Mobile Station Base Station MSC/IWF
Radio I/F
R I/F
 BSS-MSC I/F
 Fax
Adapt.
   Fax
   Fax
T.30
T.30
Adaptation
Adaptation
 function
 function
RA1
RA1'
RA1'
RA1
FEC RA2
FEC RA2
I/F Cct I/F Cct
Figure 5/03.45: Information transfer protocol model
4.2 Interactions with T.30
The philosophy of this specification is to allow the T.30 protocol to pass transparently wherever possible,
through the Fax Adaptors at both ends of the PLMN channel. Manipulations are only made to the protocol
where necessary to overcome problems resulting from the differences between the PSTN and the GSM
system. Basically, these problems fall into four categories:
- supporting facsimile on a digital connection type;
- bit errors during transfer of BCS frames;
- the need to change speed to reduce the impact of bit errors during transfer of Fax encoded
Messages;
- inability to support some features of T.30.
4.2.1 Link control strategy
Though the T.30 procedure is plain half-duplex, between the FAs at both the GSM PLMN ends a
full-duplex mode connection will be established. Information transfer is structured in fixed length blocks,
carrying either data received from the local modem, or idle synchronization patterns.
Establishment, maintenance and release of the data circuit is performed autonomously by each FA, by
properly handling the physical interface to its local modem.
Due to the rigid timeout constrains in T.30 protocol procedure, which will be actually concatenated to the
procedure defined here for the GSM connection part, a strictly forward only approach is adopted for data
link control; that is no retransmission means are explicitly introduced to recover corrupted information
blocks.
Although in the majority of cases the T.30 protocol can take care of lost frames and easily recover, there
are some particularly critical points where two consecutive segments in the procedure, without any
interposed acknowledgement, require different transmission speeds (BCS speed/Message speed).
In these cases, to grant that a correct change-over from one modem type to another takes place at both
the PLMN ends, some additional protection is necessary in the GSM environment. This protection,
actually at the beginning and at the end of the Fax page transmission, is given by means of a confirmation
mechanism, whereby the originating FA waits while transmitting a fixed pattern until an explicit
acknowledgement is received from the terminating FA. In these cases an interruption of the normal T.30
information flow may eventually result.

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Aiming at minimizing any possible delay in the end-to-end transmission between the two facsimile
apparatuses, the FAs will pass on information without error control of the message integrity (note). To this
regard, however, it is worth underlining that an essential requirement in this procedure is the detection of
some key messages exchanged between the terminals, carrying basic control information. Hence, in
parallel to the primary information passing process, a continuous monitoring of the information flowing
across the FA is necessary, to detect these messages, fully checked in their logical integrity.
NOTE: All V.21 modems in the FAs shall use the faster response time provided by CCITT
Rec. V.21 (see table 2/V.21) for OFF to ON transit
...