SIST ETS 300 603 E1:2003

European digital cellular telecommunications 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 (GSM 09.06)

....

Evropski digitalni celični telekomunikacijski sistem (faza 2) – Medsebojno delovanje med javnim kopenskim mobilnim omrežjem (PLMN) in paketno komutiranim javnim podatkovnim omrežjem/digitalnim omrežjem z integriranimi storitvami (PSPDN/ISDN) za podporo storitvam paketno komutiranega prenosa podatkov (GSM 09.06)

General Information

• 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 300 603 ed.1 (1994-09) - European digital cellular telecommunications 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 (GSM 09.06)

Standards Content (Sample)

SLOVENSKI STANDARD
SIST ETS 300 603 E1:2003
01-december-2003
(YURSVNLGLJLWDOQLFHOLþQLWHOHNRPXQLNDFLMVNLVLVWHPID]D±0HGVHERMQR
GHORYDQMHPHGMDYQLPNRSHQVNLPPRELOQLPRPUHåMHP3/01LQSDNHWQR
NRPXWLUDQLPMDYQLPSRGDWNRYQLPRPUHåMHPGLJLWDOQLPRPUHåMHP]LQWHJULUDQLPL
VWRULWYDPL363'1,6'1]DSRGSRURVWRULWYDPSDNHWQRNRPXWLUDQHJDSUHQRVD
SRGDWNRY*60
European digital cellular telecommunications 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 (GSM 09.06)
Ta slovenski standard je istoveten z: ETS 300 603 Edition 1
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)
SIST ETS 300 603 E1:2003 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST ETS 300 603 E1:2003

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SIST ETS 300 603 E1:2003
EUROPEAN ETS 300 603
TELECOMMUNICATION September 1994
STANDARD
Source: ETSI TC-SMG Reference: GSM 09.06
ICS: 33.060.30
European digital cellular telecommunications system, Global System for Mobile communications
Key words:
(GSM)
European digital cellular telecommunications 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
(GSM 09.06)
ETSI
European Telecommunications Standards Institute
ETSI Secretariat
Postal address: F-06921 Sophia Antipolis CEDEX - FRANCE
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 1994. All rights reserved.
New presentation - see History box

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ETS 300 603: September 1994 (GSM 09.06 version 4.4.1)
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
2 Normative references .7
3 Definitions and abbreviations.8
4 INTRODUCTION.10
5 NETWORK CHARACTERISTICS .11
5.1 Characteristics of GSM PLMNs.11
5.2 Characteristics of PSPDNs .11
5.3 Characteristics of ISDN .11
5.4 Characteristics of the packet service provided by the PH .11
5.5 Characteristics of the packet service provided by a PH assuming the role of an AU or
by X.32 . 11
6 INTERWORKING CLASSIFICATIONS.12
6.1 Service interworking.12
6.2 Network interworking. 12
7 NETWORK INTERWORKING SCENARIOS .12
7.1 General.12
7.2 Interworking through transit networks .12
7.3 Direct Interworking.13
8 BASIC PACKET MODE SERVICE.14
8.1 General.14
8.2 Service provided by the GSM PLMN network.14
8.3 Mobile originated calls.15
8.3.1 Subscriber on home PLMN.15
8.3.2 Subscriber on visited PLMN .15
8.4 Mobile terminated calls.17
8.4.1 Subscriber on home PLMN.17
8.4.2 Subscriber on visited PLMN .17
8.5 Mobile originated mobile terminated calls .17
8.6 Subscriber profiles .17
8.7 GSM bearer services quality of service.17
9 DEDICATED PACKET MODE SERVICE.18
9.1 General.18
9.2 General application rules .19
9.3 Specific application of rules for dedicated packet mode service .19
9.4 Mobile originated calls.20
9.4.1 General . 20
9.4.2 Short code.21
9.5 Particular packet access functionality.21
History.22

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ETS 300 603: September 1994 (GSM 09.06 version 4.4.1)
Foreword
This European Telecommunication Standard (ETS) has been produced by the Special Mobile Group
(SMG) Technical Committee (TC) of the European Telecommunications Standards
Institute (ETSI).
This ETS identifies the Interworking Functions (IWFs) and requirements for the interworking between a
GSM Public Land Mobile Network (PLMN) and a Packet Switched Public Data Network/Integrated
Services Digital Network (PSPDN/ISDN) for the support of packet services in GSM PLMNs. This ETS
corresponds to GSM technical specification GSM 09.06 version 4.4.1.
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).
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 TSs 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.

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1 SCOPE
The purpose of this specification is to identify the Interworking Functions (IWF's) and requirements for the
interworking between a GSM PLMN and a PSPDN/ISDN for the support of packet services in GSM
PLMNs.
In the GSM PLMN context the packet services are associated with bearer services and are described in
GSM 02.02. The generally defined GSM PLMN user-network access as defined in the respective GSM
TSs (see references) forms the basis for defining the particularities for the provision of packet services to
the GSM PLMN subscribers. Network internal interfaces for the support of packet services in the pan-
European ISDN are defined in ETSI standards, which are also taken as a basis.
User-network access and network internal interfaces are defined to provide the packet services.
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] GSM 01.04 (ETR 100): "European digital cellular telecommunication system
(Phase 2); Definitions, abbreviations and acronyms".
[2] CCITT Recommendation X.25: "Interface between Data Terminal Equipment
(DTE) and Data Circuit-Terminating Equipment (DCE) for terminals operating in
the packet mode and connected to Public Data Networks by dedicated circuit".
[3] CCITT Recommendation X.31: "Support of packet mode terminal equipment by
an ISDN".
[4] CCITT Recommendation X.32: "Interface between Data Terminal Equipment
(DTE) and Data Circuit-Terminating Equipment (DCE) for terminals operating in
the packet mode and accessing a Packet Switched Telephone Network or an
Integrated Services Digital Network or a Circuit Switched Public Data Network".
[5] ETS 300 007: "Integrated Services Digital Network (ISDN); Support of packet-
mode terminal equipment by an ISDN".
[6] ETS 300 099: "Integrated Services Digital Network (ISDN); Specification of the
Packet Handler access point Interface (PHI)".
[7] ETS 300 102: "Integrated Services Digital Network (ISDN); User-network
interface layer 3 Specifications for basic call control".
[8] ETR 010: "ISDN Standards Management (ISM); The ETSI basic guide onthe
European integrated services digital network".
[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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[12] GSM 02.86 (ETS 300 519): "European digital cellular telecommunication system
(Phase 2); Advice of charge (AoC) supplementary services - Stage 1".
[13] GSM 02.88 (ETS 300 520): "European digital cellular telecommunication system
(Phase 2); Call Barring (CB) supplementary services - Stage 1".
[14] GSM 03.03 (ETS 300 523): "European digital cellular telecommunication system
(Phase 2); Numbering, addressing and identification".
[15] GSM 03.10 (ETS 300 528): "European digital cellular telecommunication system
(Phase 2); GSM Public Land Mobile Network (PLMN) connection types".
[16] GSM 03.70 (ETS 300 541): "European digital cellular telecommunication system
(Phase 2); Routeing of calls to/from Public Data Networks (PDN)".
[17] GSM 04.02 (ETS 300 551): "European digital cellular telecommunication system
(Phase 2); GSM Public Land Mobile Network (PLMN) access reference
configuration".
[18] GSM 04.08 (ETS 300 557): "European digital cellular telecommunication system
(Phase 2); Mobile radio interface layer 3 specification".
[19] 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".
[20] 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".
[21] GSM 07.01 (ETS 300 582): "European digital cellular telecommunication system
(Phase 2); General on Terminal Adaptation Functions (TAF) for Mobile Stations
(MS)".
[22] GSM 07.03 (ETS 300 584): "European digital cellular telecommunication system
(Phase 2); Terminal Adaptation Functions (TAF) for services using synchronous
bearer capabilities".
[23] 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".
[24] 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)".
[25] GSM 09.07 (ETS 300 604): "European digital cellular telecommunication 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)".
3 Definitions and abbreviations
Use is made of the following terms within this specification. These terms refer to information requirements
necessary to support interworking functions, some of these terms will be identifiable with their use in other
specifications.
- Bearer capability information:

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Specific information defining the lower layer characteristics required within the network.
- Lower layer capability information:
Information defining the lower layer characteristics of the terminal.
- Higher layer capability information:
Information defining the higher layer characteristics of a teleservice active on the terminal.
- Protocol identifier:
Information defining the specific protocols utilised for the support of data transfer by a terminal.
- Service profile:
Set of values of the network default and user selectable attributes selected for a particular DTE
identity.
- Loop detection:
Detection of the situation, where a call, which has left the originating network, re-appears at the
originating network.
- GSM packet mode services "Use of X.31 case A":
A circuit connection shall be used for accessing the packet service (according to ETS 300 099), with
the significant characteristics of the connection identified by the following setting of the respective
parameters of the Bearer Capability Information Element:
* information transfer capability = unrestricted digital information
* transfer mode = circuit mode.
The issue of "loop detection" is of no concern in the case of X.31 Case A (ETS 300 099) because
the PH inserts - irrespective of being accessed by a home or a foreign roaming subscriber - into the
"calling address" of an outgoing X.25 "call request" packet the address of the B-channel port.
- Packet mode services via PSTN (X.32):
A circuit connection shall be used for accessing the packet service with the significant characteristics
of the connection identified by the following setting of the respective parameters of the Bearer
Capability Information Element in access from a PLMN:
* information transfer capability = 3.1kHz exPLMN
* transfer mode = circuit mode.
- Home PLMN:
That GSM PLMN where the mobile subscriber has his subscription for mobile services.
- Visited PLMN:
That GSM PLMN on which the mobile subscriber is roamed to when leaving his home PLMN
(HPLMN) and logged-in there.
- Basic MSisdn:
The MSisdn stored in VLR for a visiting mobile subscriber.
- PSPDN port:
Unit providing incoming/outgoing demand access to a PSPDN (X.32).

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Term Specification where defined
CCITT, ETS GSM
Bearer service I.112, I.210, I.211 02.02
Exchange I.112
Terminal Adaptor (Functions) I.411 07 series
Interworking Function X.300 09.06,09.07
Attributes I.112,I.140, I.211 02.01
Connection capabilities I.340 03.10
Control channel (D/Dm channel) I.412 04.03
Traffic channel (B/TCH channel) I.412 04.03
Service profile ETS 300 099 09.06
Table 1/GSM09.06 Specification reference list
In addition to those below abbreviations used in this specification are listed in GSM 01.04.
AU Access Unit
Cct Circuit
CRP Call Request Packet
IWMSC MSC accessing the PH
4 INTRODUCTION
General Network Interworking Scenarios are described in GSM 09.01.
When two dissimilar networks are required to interwork in order to support a communication between two
subscribers, one on each network, a number of functions performing the interworking 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 of specific packet functions
ii) the need of modem pools and network-based rate adaptation.
From the mobile subscriber's point of view, there have been defined two types of services within GSM
PLMNs:
- basic packet mode services:
These services provide access either to the Packet handler(PH) and/or the PSPDN Port to which
the individual subscriber is subscribed to.
- dedicated packet mode services:
These services provide access to the PH provided by the visited GSM PLMN, i.e. the "real packet
world" is entered as soon as possible.
Packet services are provided in the context of this specification by means of the "circuit" transfer mode.
For the purposes of determining the required IWF functionality, it is necessary, however, to consider
separately each type of service i.e. the basic and the dedicated packet mode service.

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5 NETWORK CHARACTERISTICS
The key characteristics of networks concerned are listed in Table 3/09.06.
5.1 Characteristics of GSM PLMNs
The GSM PLMN is fully defined in the GSM series of specifications.
5.2 Characteristics of PSPDNs
These are defined in the relevant CCITT X series recommendations, such as X.1, X.2, X.10, X.25, and
X.75.
5.3 Characteristics of ISDN
These are defined in the CCITT I-series recommendations. The services and standards for the pan-
European ISDN are identified in ETR 010.
5.4 Characteristics of the packet service provided by the PH
The packet services supported via the packet handler interface (PHI) are defined in ETS 300 099. Support
for both the ISDN X.31 Case A and Case B are specified there.
Characteristics GSM PLMN ISDN PSPDN
User-network interface Digital Digital
User-network signalling GSM 04.08 I.441/I.451 X.25, X.31, X.32
User-terminal equipment MT0, Digital TE DTE
support DTE+MT1, (ISDN NT,
DTE+MT2 TE1 or TE2+TA)
see GSM 04.02 see I.441
Inter-exchange SS No.7 SS No.7 Proprietary,
signalling ISUP,TUP+, ISUP, TUP+ X.75
MAP X.75
Transmission facilities Digital Digital Digital
Exchange types Digital Digital Digital
Information transfer mode Circuit Cct or Packet
Information transfer Speech, Speech, unrestr.digital
capabilities unrestr.digital, unrestr.digital
altern. speech/ 3.1kHz audio
fax group 3, etc. video, etc.
Table 3/GSM09.06 Key characteristics of networks concerned
5.5 Characteristics of the packet service provided by a PH assuming the role of an AU or by
X.32
The packet services provided by the PH assuming the role of an AU is defined in the ETS 300 099 (X.31
Case A). The packet service provided via a modem is defined in CCITT X.32.

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6 INTERWORKING CLASSIFICATIONS
Generally the distinction is made between the service interworking and the network interworking.
6.1 Service interworking
Service interworking is required when the Teleservices at the calling and called terminals are different (e.g.
Teletex interworking with facsimile). These aspects are not dealt with in this specification.
6.2 Network interworking
Network interworking is required whenever a GSM PLMN and a non-GSM PLMN together are involved to
provide an end to end connection and may be required in instances of GSM PLMN to GSM PLMN
connections. The first case applies to the subject matter of this specification and thus dealt with herein
after.
7 NETWORK INTERWORKING SCENARIOS
7.1 General
There are two sets of routing scenarios for connecting a GSM PLMN to a PSPDN/ISDN, namely
- via a transit ISDN or PSTN or
- direct connection.
These are identified in GSM 03.70.
What concerns the numbering please see GSM 03.03, GSM 03.70, and ETS 300 099.
7.2 Interworking through transit networks
In this scenario an packet handler or an PSPDN port is considered to be part of the ISDN or the PSPDN,
as shown in Figures 1 and 2/GSM09.06.
Figure 1/GSM09.06 shows the access to a conventional X.32 PSPDN port of the PSPDN via transit
networks ISDN and/or PSTN. The information transfer capability attribute value indicated in the GSM
PLMN is "3.1kHz audio, ex PLMN". In this case, modems are used.
Figure 2/GSM09.06 shows the access to the packet mode service provided according to the concept of
the ETSI Packet Handler (PH) with AU functionality as specified in ETS 300 099 section 5 for Case A. The
information transfer capability attribute value is "unrestricted digital information". The application of this
scenario requires an arrangement with the ISDN operator for granting access to the PH for GSM PLMN
subscribers.
The procedures used for mobile originated and mobile terminated calls to establish the circuit connection
are defined in sections 8 and 9 for the basic and dedicated packet services, respectively.

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    �˝˝˝˝˝˝˝˝˝˝˝˝˝» �˝˝˝˝˝˝˝˝˝˝˝˝˝˝˝»
    ”    PLMN ” ”     ISDN ”
�˜˜˜¿  ”�˜˜˜˜˜¿   ” ”        ”
‡MS -----‡MSC-A‡----------------+    ”
�˜˜˜�  ”‡/IWF ‡   ” ”   ‡    ”
    ”‡MODEM‡-------+ ”   ‡    ”
    ”�˜˜˜˜˜�   ”‡ ”   ‡    ”
    ¨˝˝˝˝˝˝˝˝˝˝˝˝˝…‡ ¨˝˝˝˝˝˝‡˝˝˝˝˝˝˝˝…
            ‡    ‡
            ‡    ‡
            ‡ �˝˝˝˝˝˝‡˝˝˝˝˝˝˝˝» �˜¿ �˝˝˝˝˝˝˝˝˝˝˝˝˝˝˝»
            ‡ ”   ‡ PSTN ” ‡M‡ ”    PSPDN  ”
            ‡ ”   ‡    ” ‡O‡ ˙˜˜˜˜˜˜¿    ”
            ‡ ”   +----------‡D‡-- PSPDN‡    ”
            ‡ ”        ” ‡E‡ ” port ‡    ”
            +-------------------‡M‡ ˙˜˜˜˜˜˜�    ”
             ¨˝˝˝˝˝˝˝˝˝˝˝˝˝˝˝… �˜� ¨˝˝˝˝˝˝˝˝˝˝˝˝˝˝˝…
Figure 1/GSM09.06 Interworking through ISDN and PSTN (3,1kHz exPLMN)
    �˝˝˝˝˝˝˝˝˝˝˝˝˝» �˝˝˝˝˝˝˝˝˝˝˝˝˝˝˝»   �˝˝˝˝˝˝˝˝˝˝˝˝˝˝˝»
    ”    PLMN ” ” ISDN     ” PHI ”        ”
�˜˜˜¿  ”�˜˜˜˜˜¿   ” ”     �˜˜˜˜˜¶ ‡ ”˜˜˜˜¿ PSPDN  ”
‡MS -----‡MSC-A‡----------------------------‡--- PH ‡     ”
�˜˜˜�  ”‡/IWF ‡   ” ”     ‡CRF-P” ‡ ˙˜˜˜˜�     ”
    ”�˜˜˜˜˜�   ” ”     �˜˜˜˜˜¶   ”        ”
    ¨˝˝˝˝˝˝˝˝˝˝˝˝˝… ¨˝˝˝˝˝˝˝˝˝˝˝˝˝˝˝…   ¨˝˝˝˝˝˝˝˝˝˝˝˝˝˝˝…
Figure 2/GSM09.06 Interworking through ISDN (unrestricted digital information)
Note: The packet handler logically is a part of the ISDN.
7.3 Direct Interworking
In this scenario the PH logically is part of the GSM PLMN (Figure 3/GSM09.06) and may be physically
located in the GSM PLMN, the PSPDN or the ISDN. In the latter two cases, an arrangement with the
PSPDN or ISDN operators is required in order to arrange for GSM PLMN particularities for dedicated
access to cope with the "loop detection" issue.
The interface between the MSC and the PH shall be the PH interface (PHI) as specified in ETS 300 099
for Case A. In cases where the available PH only supports the ISDN X.31 Case B, the PH is required to
perform a GSM specific function, i.e. to substitute in the X.25 "call request" packet the PH port address in
place of a foreign subscribers calling address. The GSM PLMN shall take care of the X.31 Case A/B
conversion in order to proceed the call.
    �˝˝˝˝˝˝˝˝˝˝˝˝˝˝˝˝˝»           �˝˝˝˝˝˝˝˝˝˝˝˝˝˝˝»
    ”      PLMN ”           ”        ”
�˜˜˜¿  ”�˜˜˜˜¿ PHI �˜˜˜¿ ”     ‡      ”   PSPDN  ”
‡MS -----‡MSC ‡--‡--‡PH ‡-----------‡------------        ”
�˜˜˜�  ”‡/IWF‡ ‡ �˜˜˜� ”     ‡      ”        ”
    ”�˜˜˜˜�      ”    X.75 or    ”        ”
    ¨˝˝˝˝˝˝˝˝˝˝˝˝˝˝˝˝˝…    propriatory  ¨˝˝˝˝˝˝˝˝˝˝˝˝˝˝˝…
Figure 3/GSM09.06 Direct interworking
Mobile originated and mobile terminated call procedures are defined in sections 8 and 9.

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8 BASIC PACKET MODE SERVICE
8.1 General
Basic packet mode services are the services offered to the mobile users, as described in GSM 02.02, 3x-
series. Offering the basic packet mode services requires that GSM PLMNs support the demand access to
the PSPDN port in the PSPDN according to CCITT X.32 or to a packet handler of the ISDN (X.31 Case A).
See note. This may be either in the network associated with the home PLMN of the respective mobile
subscriber or in any other network to which the subscriber is entitled to establish calls.
Note: The Case B is currently not feasible within GSM PLMNs because this case neither allows for
addressing of PHs of different providers of packet switched data transmission services nor enables the
handling of connections for roaming subscribers. The missing prerequisites for accomplishing this
functionality in X.31 Case B are
- for calls from roaming foreign subscribers to the home PH --> support of the according addresses
and
- for calls to roaming foreign subscribers via the PH, --> the PSPDN to provide redirection functionality
as the gateway of home PLMNs does for routing circuit switched calls for their roaming subscribers.
The scenarios described in section 7 shall apply.
The mobile user may have to subscribe separately to the services offered by the PSPDN port of a PSPDN
or by the PH of the ISDN or PSPDN and/or home PLMN, which may depend on the policy or agreements
reached between GSM PLMN operator and ISDN or PSPDN operators.
The GSM PLMN networks shall provide only the circuit connection to/from the PH or the PSPDN port. The
routing is based on the E.164/E.163 numbering plan because the location of both PH and PSPDN port is
identified by E.164/E.163 numbers. Once the connection to the PH or PSPDN port has been established
the GSM PLMN is transparent for the user information and in-band control information.
The mobile user shall set in the SETUP message the GSM BC-IE, LLC-IE, and HLC-IE according to GSM
07.01 for 30-series type of services and the applicable variant and shall insert as the called address the
E.164/E.163 number associated with the PH or the PSPDN port. That kind of access allows for mobile
users to use customized and standard profiles according to CCITT X.32. These profiles are invisible to the
GSM PLMNs. The characteristics of the service are those offered via the packet handler interface for X.31
Case A.
The address of the called subscriber for mobile originated calls is sent to the PH or PSPDN port in the
"called address" field of the X.25 CALL REQUEST packet and is a number in the for
...