ETSI ETS 300 975 ed.1 (1997-05)

Digital cellular telecommunications system (Phase 2+) (GSM); 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 version 5.0.2)

DE/SMG-040906Q

Digitalni celični telekomunikacijski sistem (faza 2+) – Medsebojno delovanje javnega kopenskega mobilnega omrežja (PLMN) in paketno komutiranega javnega podatkovnega omrežja/digitalnega omrežja z integriranimi storitvami (PSPDN/ISDN) kot podpora paketno komutiranim storitvam prenosa podatkov (GSM 09.06, različica 5.0.2)

General Information

• Status: Published
• Publication Date: 02-Jun-1997
• Technical Committee: SMG 4 - Data Services
• Current Stage: 12 - Completion
• Due Date: 25-Apr-1997
• Completion Date: 03-Jun-1997
• Ref Project: SIST ETS 300 975 E1:2003 - Digital cellular telecommunications system (Phase 2+) (GSM); 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 version 5.0.2)

Standards Content (Sample)

SLOVENSKI STANDARD
SIST ETS 300 975 E1:2003
01-december-2003
'LJLWDOQLFHOLþQLWHOHNRPXQLNDFLMVNLVLVWHPID]D±0HGVHERMQRGHORYDQMH
MDYQHJDNRSHQVNHJDPRELOQHJDRPUHåMD3/01LQSDNHWQRNRPXWLUDQHJDMDYQHJD
SRGDWNRYQHJDRPUHåMDGLJLWDOQHJDRPUHåMD]LQWHJULUDQLPLVWRULWYDPL
363'1,6'1NRWSRGSRUDSDNHWQRNRPXWLUDQLPVWRULWYDPSUHQRVDSRGDWNRY
*60UD]OLþLFD
Digital cellular telecommunications system (Phase 2+) (GSM); 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 version 5.0.2)
Ta slovenski standard je istoveten z: ETS 300 975 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 300 975 E1:2003 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST ETS 300 975 E1:2003

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SIST ETS 300 975 E1:2003
EUROPEAN ETS 300 975
TELECOMMUNICATION May 1997
STANDARD
Source: ETSI TC-SMG Reference: DE/SMG-040906Q
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+);
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 version 5.0.2)
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: [e-mail]
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 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
1 Scope .7
2 Normative references.7
3 Definitions and abbreviations .9
4 Introduction.10
5 Network characteristics .10
5.1 Characteristics of GSM PLMNs.10
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 .11
6.1 Service interworking.11
6.2 Network interworking .11
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 .13
8.1 General .13
8.2 Service provided by the GSM PLMN network.14
8.3 Mobile originated calls .14
8.3.1 Subscriber on home PLMN .14
8.3.2 Subscriber on visited PLMN .14
8.4 Mobile terminated calls .16
8.4.1 Subscriber on home PLMN .16
8.4.2 Subscriber on visited PLMN .16
8.5 Mobile originated mobile terminated calls.16
8.6 Subscriber profiles .16
8.7 GSM bearer services quality of service .16
9 Dedicated packet mode service.17
9.1 General .17
9.2 General application rules .18
9.3 Specific application of rules for dedicated packet mode service .18
9.4 Mobile originated calls .19
9.4.1 General.19
9.4.2 Short code .20
9.5 Particular packet access functionality.20
History.21

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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 within the
digital cellular telecommunications system (Phase 2/Phase 2+).
This ETS is a GSM technical specification version 5, which incorporates GSM Phase 2+
enhancements/features to the version 4 GSM technical specification. The ETS from which this Phase 2+
ETS has evolved, is Phase 2 GSM ETS 300 603 + Amendment 1 (GSM 09.06 version 4.5.0).
The specification from which this ETS has been derived was originally based on CEPT documentation,
hence the presentation of this ETS may not be entirely in accordance with the ETSI/PNE Rules.
The contents of this ETS are subject to continuing work within TC-SMG and may change following formal
TC-SMG approval. Should TC-SMG modify the contents of this ETS it will then 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.
Transposition dates
Date of adoption: 4 April 1997
Date of latest announcement of this ETS (doa): 31 August 1997
Date of latest publication of new National Standard
or endorsement of this ETS (dop/e): 28 February 1998
Date of withdrawal of any conflicting National Standard (dow): 28 February 1998

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1 Scope
This European Telecommunication Standard (ETS) identifies the Interworking Functions (IWF's) and
requirements for the interworking between a GSM PLMN and a Packet Switched Public Data
Network/Integrated Services Digital Network (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
specifications (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 350): "Digital cellular telecommunications system (Phase 2+);
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 Specification Description
Language (SDL) diagrams".
[8] ETR 010: "ISDN Standards Management (ISM); The ETSI basic guide on the
European integrated services digital network".
[9] GSM 02.02 (ETS 300 904): "Digital cellular telecommunications system
(Phase 2+); Bearer Services (BS) supported by a GSM Public Land Mobile
Network (PLMN)".
[10] GSM 02.03 (ETS 300 905): "Digital cellular telecommunications system
(Phase 2+); Teleservices supported by a GSM Public Land Mobile Network
(PLMN)".
[11] GSM 02.04 (ETS 300 918): "Digital cellular telecommunications system
(Phase 2+); General on supplementary services".

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[12] GSM 02.86: "Digital cellular telecommunications system; Advice of charge
(AoC) Supplementary Services - Stage 1".
[13] GSM 02.88: "Digital cellular telecommunications system; Call Barring (CB)
Supplementary Services - Stage 1".
[14] GSM 03.03 (ETS 300 927): "Digital cellular telecommunications system
(Phase 2+); Numbering, addressing and identification".
[15] GSM 03.10: "Digital cellular telecommunications system (Phase 2+); GSM
Public Land Mobile Network (PLMN) connection types".
[16] GSM 03.70: "Digital cellular telecommunications system; Routeing of calls
to/from Public Data Networks (PDN) and the GSM Public Land Mobile Network
(PLMN)".
[17] GSM 04.02: "Digital cellular telecommunications system (Phase 2+); GSM
Public Land Mobile Network (PLMN) access reference configuration".
[18] GSM 04.08 (ETS 300 940): "Digital cellular telecommunications system
(Phase 2+); Mobile radio interface layer 3 specification".
[19] GSM 04.21 (ETS 300 945): "Digital cellular telecommunications system
(Phase 2+); Rate adaption on the Mobile Station - Base Station System (MS -
BSS) Interface".
[20] GSM 04.22 (ETS 300 946): "Digital cellular telecommunications 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 300 913): "Digital cellular telecommunications system
(Phase 2+); General on Terminal Adaptation Functions (TAF) for Mobile
Stations (MS)".
[22] GSM 07.03 (ETS 300 915): "Digital cellular telecommunications system
(Phase 2+); Terminal Adaptation Functions (TAF) for services using
synchronous bearer capabilities".
[23] GSM 08.20: "Digital cellular telecommunications system (Phase 2+); Rate
adaption on the Base Station System - Mobile-services Switching Centre (BSS -
MSC) interface".
[24] GSM 09.03: "Digital cellular telecommunications system; 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 300 976): "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)".

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3 Definitions and abbreviations
Use is made of the following terms within this ETS. These terms refer to information requirements
necessary to support interworking functions, some of these terms will be identifiable with their use in other
specifications.
For the purposes of this ETS, the following definitions apply:
bearer capability information: 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 BC-IE:
- 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.
GSM packet mode services "Use of X.31 case B": A packet 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 BC-IE:
- information transfer capability = unrestricted digital information;
- transfer mode = packet mode.
service number: A service number is a special E.164 number of the HPLMN which indicates to the
HPLMN that, in case of an access to a PH X.31 case B, case A/B conversion is necessary. It is translated
in the HPLMN into the actual E.164 number of the PH. The service number is used by the subscriber for
the access of the PH case B when the subscriber is in the HPLMN or in the VPLMN.
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 = 3,1 kHz 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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Table 1/GSM 09.06: Specification reference list
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
In addition to those below, abbreviations used in this ETS 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 ETS 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.
5 Network characteristics
The key characteristics of networks concerned are listed in table 2/09.06.
5.1 Characteristics of GSM PLMNs
The GSM PLMN is fully defined in the GSM series of specifications.

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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.
Table 2/GSM 09.06: Key characteristics of networks concerned
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/ 3.1 kHz audio
fax group 3, etc. video, etc.
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.
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 ETS.
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 ETS and thus dealt with herein after.

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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 PH or an PSPDN port is considered to be part of the ISDN or the PSPDN, as shown in
figures 1 and 2/GSM 09.06."
Figure 1/GSM 09.06 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 "3.1 kHz audio, ex PLMN". In this case, modems are used.
Figure 2/GSM 09.06 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 clause 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.
"PHs supporting only X.31 case B can also be used. For these PHs agreements should exist between the
PLMN and the fixed network operators to signal the case B between PLMN and ISDN. The GSM HPLMN
shall take care of the X.31 case A/B conversion in order to proceed the call. The location of this
conversion within the HPLMN is network dependent." The procedures used for mobile originated and
mobile terminated calls to establish the circuit connection are defined in clauses 8 and 9 for the basic and
dedicated packet services, respectively.
PLMN
ISDN
MSC-A
MS
/IWF
MODEM
M
PSTN
PSPDN
O
PSPDN
D
port
E
M
Figure 1/GSM 09.06: Interworking through ISDN and PSTN (3,1 kHz exPLMN)
PHI
PLMN ISDN
PSPDN
MS MSC-A
PH
CRF-P
/IWF
Figure 2/GSM 09.06: Interworking through ISDN (unrestricted digital information)
NOTE: The packet handler logically is a part of the ISDN.

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7.3 Direct Interworking
In this scenario the PH logically is part of the GSM PLMN (figure 3/GSM 09.06) 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
MSC PH
MS
/IWF
X.75 or
propriatory
Figure 3/GSM 09.06: Direct interworking
Mobile originated and mobile terminated call procedures are defined in clauses 8 and 9.
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 clause 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.

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