SIST-V ETSI/EG 201 018 V1.5.2:2005

• Abstract:

  Editorial correction only. To correct erroneous subclause numbering.

• Status: Published
• Publication Date: 31-Mar-2005
• Withdrawal Date: 30-Sep-2003
• ICS: 33.080 - Integrated Services Digital Network (ISDN)
• Technical Committee: SPN - Services and Protocols for Networks
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 01-Apr-2005
• Due Date: 01-Apr-2005
• Completion Date: 01-Apr-2005
• Ref Project: ETSI EG 201 018 V1.5.2 (1998-11) - Integrated Services Digital Network (ISDN); Application of the Bearer Capability (BC), High Layer Compatibility (HLC) and Low Layer Compatibility (LLC) information elements by terminals supporting ISDN services

SIST-V ETSI/EG 201 018 V1.5.2:2005 is the Slovenian adoption of ETSI Guide EG 201 018 Version 1.5.2, published by SIST. It explains how Integrated Services Digital Network (ISDN) terminals use the Bearer Capability (BC), High Layer Compatibility (HLC) and Low Layer Compatibility (LLC) information elements when setting up and recognising services in a demand-mode ISDN environment. The guide is aimed at terminal designers, service specialists, test writers and interoperability teams that need to choose the right ISDN code points.

What does SIST-V ETSI/EG 201 018 V1.5.2:2005 specify?

SIST-V ETSI/EG 201 018 V1.5.2:2005 gives supplementary guidance on the use of BC, HLC and LLC for individual public ISDN telecommunication services. It is organized as a short framework followed by service-by-service coding examples, then interworking cases for non-European ISDNs and non-ISDN networks.

The document is arranged as follows:

• Clause 1: Scope
• Clause 2: References
• Clause 3: Abbreviations
• Clause 4: General principles applicable to all services
• Clause 5: Impact of interworking situations
• Clause 6: Request and recognition of a basic telecommunication service in an ISDN environment
• Clause 7: Coding examples applicable to specific user applications
• Clause 8: Interworking with non-European ISDNs supporting restricted 64 kbit/s transfer capability
• Clause 9: Codings in the case where non-ISDNs are involved
• Annex A: Informative bibliography

The guidance is for public ISDNs and the examples assume a pure ISDN environment unless the clause is specifically about interworking. The document also concentrates on how terminals should request a service and how the called terminal should recognise it.

What are the key requirements of SIST-V ETSI/EG 201 018 V1.5.2:2005?

SIST-V ETSI/EG 201 018 V1.5.2:2005 is mainly a coding guide: it shows which BC, HLC and LLC values should be used for a given service, and how the called side should interpret them. The practical value is that a terminal can set up the right ISDN call profile and then accept or reject incoming calls consistently.

General rules in Clause 4

• LLC is transferred transparently through the ISDN, although some networks may check its length.
• HLC is also transferred transparently, but a network may inspect it to associate a supplementary service with a teleservice.
• When a bearer service is used, HLC is normally absent unless the bearer service is also carrying a high-layer application.
• In special terminal arrangements, address information alone may be used, and Multiple Subscriber Number (MSN) is then the relevant supplementary service.
• A Terminal Equipment type 2 (TE2) with a Terminal Adapter (TA) is treated as functionally equivalent to a Terminal Equipment type 1 (TE1), and the TA should not generate a progress indicator when it sets up the connection.

Call setup examples in Clause 6

• Clause 6 gives typical codings for speech, 64 kbit/s unrestricted and 64 kbit/s 8 kHz structured bearer services, packet mode bearer services, and common teleservices.
• For the called terminal, compatibility checking is based on BC, and on HLC and LLC where they are present.
• If BC and LLC carry overlapping information and conflict, the BC information wins and the conflicting LLC content is ignored.
• For packet mode access through the B-channel or D-channel, the examples show X.25-related layer 2 and layer 3 coding, and LLC is absent.
• For teleservices such as telephony 3.1 kHz, Telefax G4, syntax-based videotex, telephony 7 kHz, videotelephony, facsimile group 2/3, FTAM, Euro file transfer, videoconference, audiographic conference and multimedia services, the document shows the expected BC and HLC combinations for both the calling and called sides.

Fallback, repeated information elements and short-term procedures

• For videotelephony, videoconference, audiographic conference and multimedia services, the guide shows how repeated BC and HLC information elements are used when fallback to telephony 3.1 kHz or 7 kHz is allowed.
• The same clauses also show “short term procedures” where the network cannot provide fallback, tones or announcements, and the call is not recognised as the richer audiovisual service.
• For several services, the LLC element may be present only when fallback is not permitted; when present, it may be used for compatibility checking or ignored if it duplicates BC content.

Interworking clauses

• Clause 8 gives examples for interworking with non-European ISDNs that support restricted 64 kbit/s transfer capability.
• Clause 9 gives examples for calls between ISDN and PSTN, PSPDN and CSPDN environments.
• These clauses matter when terminals must work across different national or network domains, not just inside one ISDN.

What terms does SIST-V ETSI/EG 201 018 V1.5.2:2005 define?

• Bearer Capability (BC) - The information element that identifies the bearer service requested or provided in the call setup.
• High Layer Compatibility (HLC) - The information element that identifies the high-layer application or teleservice so the far end can recognise the service type.
• Low Layer Compatibility (LLC) - The information element that carries lower-layer details such as rate adaptation or protocol profile.
• Terminal Adapter (TA) - Equipment that adapts TE2 terminal equipment to the ISDN user-network interface.
• Terminal Equipment type 1 (TE1) - ISDN-native terminal equipment that connects directly to the ISDN interface.
• Terminal Equipment type 2 (TE2) - Non-ISDN terminal equipment that needs a TA to connect to ISDN.
• Multiple Subscriber Number (MSN) - A supplementary service used when special terminal arrangements depend on address information only.
• Public Switched Telephone Network (PSTN) - The conventional telephone network used in the interworking examples with ISDN.

Who uses SIST-V ETSI/EG 201 018 V1.5.2:2005?

SIST-V ETSI/EG 201 018 V1.5.2:2005 is used by ETSI committees, terminal manufacturers, TA suppliers, network engineers and test authors who need to align ISDN call coding with service behaviour. It is especially useful when a product must interoperate across public ISDNs or across ISDN and non-ISDN networks.

Typical users include:

• terminal and TA designers selecting BC, HLC and LLC values
• service engineers defining how a terminal should request or recognise a teleservice
• interoperability and conformance teams checking SETUP message coding
• buyers or quality managers verifying that a terminal supports the intended ISDN service profile
• teams working with telephony, fax, videotex, X.25-based data, videoconference and multimedia applications

What changed in SIST-V ETSI/EG 201 018 V1.5.2:2005 from the previous edition?

SIST-V ETSI/EG 201 018 V1.5.2:2005 replaces the fourth edition of ETR 018 issued in March 1995. The foreword states that the updated guide adds examples for videoconferencing, audiographic conferencing and multimedia services, and the scope says this version is an editorial correction to fix erroneous subclause numbering.

Which standards are used with SIST-V ETSI/EG 201 018 V1.5.2:2005?

SIST-V ETSI/EG 201 018 V1.5.2:2005 is based on EN 300 403-1, which provides the DSS1 basic call control rules and the compatibility and parameter-negotiation annexes used throughout the guide. It also depends on a set of service and protocol standards that define the applications shown in the examples.

• EN 300 403-1 - core call control, BC/HLC/LLC bit patterns, and annex B and J behaviour
• ETS 300 080 - lower layer protocols for telematic terminals and application rules used in teletex, X.75, FTAM and Eurofile examples
• ETS 300 218 - syntax-based videotex lower layers for ISDN packet mode
• ETS 300 264 - videotelephony teleservice description
• ETS 300 267 - telephony 7 kHz, videotelephony, audiographic conference and videoconference teleservices
• ETS 300 383 and ETS 300 388 - Euro file transfer and FTAM over ISDN profiles
• F.184, F.200, F.220, F.230, T.90 and F.700 - facsimile, teletex, telematic and multimedia service definitions
• V.110, X.25, X.30, X.31, X.75, ISO/IEC 7776 and ISO/IEC 8208 - rate adaptation and packet-layer protocols used in the data and file-transfer examples

What does the SIST-V ETSI/EG 201 018 V1.5.2:2005 document contain?

The document is built around SETUP-message coding examples. It shows how BC, HLC and LLC are populated for calling and called terminals, including when a field is omitted, repeated or used for compatibility checking.

Clause 6 contains the main service codings, including speech, unrestricted 64 kbit/s, packet-mode access, telephony, fax, videotex, videotelephony, conference and multimedia cases. Clause 7 adds user-application examples such as V.110/X.30 terminal adaptation, X.25 access, teletex terminals and voice-band data via modem.

The later clauses are especially practical for interoperability work because they show how to handle fallback, short-term procedures, interworking with restricted 64 kbit/s networks, and calls involving the PSTN, PSPDN and CSPDN. Annex A is a bibliography that points to supporting ETSI, ITU-T, CCITT and ISO/IEC documents used by the examples.

SLOVENSKI STANDARD
01-april-2005
Digitalno omrežje z integriranimi storitvami (ISDN) - Uporaba informacijskih
elementov: nosilna zmožnost (BC), združljivost zgornjih plasti (HLC) in združljivost
spodnjih plasti (LLC) v terminalih, ki podpirajo storitve ISDN
Integrated Services Digital Network (ISDN); Application of the Bearer Capability (BC),
High Layer Compatibility (HLC) and Low Layer Compatibility (LLC) information elements
by terminals supporting ISDN services
Ta slovenski standard je istoveten z: EG 201 018 Version 1.5.2
ICS:
33.080 Digitalno omrežje z Integrated Services Digital
integriranimi storitvami Network (ISDN)
(ISDN)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EG 201 018 V1.5.2 (1998-11)
ETSI Guide
Integrated Services Digital Network (ISDN);
Application of the Bearer Capability (BC),
High Layer Compatibility (HLC) and
Low Layer Compatibility (LLC) information elements
by terminals supporting ISDN services

2 EG 201 018 V1.5.2 (1998-11)
Reference
REG/SPS-05207 (9fc00jpe.PDF)
Keywords
ISDN, DSS1, coding, BC, LLC, HLC, IE
ETSI
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Copyright Notification
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The copyright and the foregoing restriction extend to reproduction in all media.
© European Telecommunications Standards Institute 1998.
All rights reserved.
ETSI
3 EG 201 018 V1.5.2 (1998-11)
Contents
Intellectual Property Rights.6
Foreword .6
Introduction .6
1 Scope.8
2 References.8
3 Abbreviations.9
4 General principles applicable to all services.10
5 Impact of interworking situations .11
5.1 Incoming calls from non-ISDNs . 11
5.2 BC and LLC application guidelines. 11
6 Request and recognition of a basic telecommunication service in an ISDN environment .12
6.1 Request and recognition of a circuit-mode bearer service . 12
6.1.1 Circuit-mode 64 kbit/s 8 kHz structured bearer service category usable for speech information
transfer . 12
6.1.1.1 Request by a calling terminal equipment . 12
6.1.1.2 Compatibility at the called terminal equipment . 12
6.1.2 Circuit-mode 64 kbit/s unrestricted 8 kHz structured bearer service category. 13
6.1.2.1 Request by a calling terminal equipment . 13
6.1.2.2 Compatibility at the called terminal equipment . 13
6.1.3 Circuit-mode 64 kbit/s 8 kHz structured bearer service category usable for 3,1 kHz audio
information transfer. 14
6.1.3.1 Request by a calling terminal equipment . 14
6.1.3.2 Compatibility at the called terminal equipment . 14
6.1.4 Circuit-mode multiple-rate unrestricted 8 kHz structured bearer service category . 15
6.1.4.1 Request by a calling terminal equipment . 15
6.1.4.2 Compatibility at the called terminal equipment . 15
6.2 Packet mode bearer service categories. 16
6.2.1 Virtual call bearer services (support of X.25 terminal equipment allowing access to the ISDN virtual
circuit service (ITU-T Recommendation X.31, Case B)). 16
6.2.1.1 Access through the B-channel . 16
6.2.1.1.1 Request by a calling terminal equipment . 16
6.2.1.1.2 Compatibility at the called terminal equipment. 16
6.2.1.2 Access through the D-channel . 17
6.2.1.2.1 Request by a calling terminal equipment . 17
6.2.1.2.2 Compatibility at the called terminal equipment. 17
6.3 Request and recognition of a teleservice. 17
6.3.1 Telephony 3,1 kHz teleservice . 17
6.3.1.1 Request by a calling terminal equipment . 17
6.3.1.2 Compatibility at the called terminal equipment . 18
6.3.2 Telefax G4 service (using circuit-mode bearer capability). 18
6.3.2.1 Request by a calling terminal equipment . 18
6.3.2.2 Compatibility at the called terminal equipment . 19
6.3.3 Syntax-based videotex teleservice. 21
6.3.3.1 Access to the syntax-based videotex teleservice using an end-to-end circuit-switched connection. 21
6.3.3.1.1 Request by a calling terminal equipment . 21
6.3.3.1.2 Compatibility at the called terminal equipment. 22
6.3.3.2 Access to the syntax-based videotex teleservice via a PSPDN access unit (ITU-T
Recommendation X.31, Case A) . 24
6.3.3.2.1 Request by a calling terminal equipment . 24
6.3.3.2.2 Compatibility at the called terminal equipment. 25
6.3.3.3 Access to the syntax-based videotex teleservice using a packet-switched connection through the
B-channel. 25
ETSI
4 EG 201 018 V1.5.2 (1998-11)
6.3.3.3.1 Request by a calling terminal . 26
6.3.3.3.2 Compatibility at the called terminal equipment. 26
6.3.3.4 Access to the syntax-based videotex service using a packet-switched connection through the
D-channel . 26
6.3.3.4.1 Request by a calling terminal using the D-channel . 26
6.3.3.4.2 Compatibility at the called terminal equipment. 27
6.3.4 Telephony 7 kHz teleservice . 27
6.3.4.1 Request by a calling terminal equipment . 27
6.3.4.2 Compatibility at the called terminal equipment . 28
6.3.5 Videotelephony teleservice . 29
6.3.5.1 Codings required for the service specified in ETS 300 264 . 29
6.3.5.1.1 First connection. 29
6.3.5.1.2 Second connection . 31
6.3.5.2 Codings required for short term procedures . 32
6.3.5.2.1 Request by a calling terminal equipment . 32
6.3.5.2.2 Compatibility at the called terminal equipment. 33
6.3.6 Facsimile group 2/3 service. 34
6.3.6.1 Request by a calling terminal equipment . 34
6.3.6.2 Compatibility at the called terminal equipment . 35
6.3.7 File transfer & access management (FTAM) teleservice. 35
6.3.7.1 Request by a calling terminal equipment . 35
6.3.7.2 Compatibility at the called terminal equipment . 36
6.3.8 Euro file transfer teleservice. 37
6.3.8.1 Request by a calling terminal. 37
6.3.8.2 Compatibility at the called terminal equipment . 39
6.3.9 Videoconference teleservice. 40
6.3.9.1 Codings required for the service specified in ETS 300 267 . 40
6.3.9.1.1 First connection. 40
6.3.9.1.2 Second connection . 42
6.3.9.2 Codings required for short term procedures . 43
6.3.9.2.1 Request by a calling terminal equipment . 43
6.3.9.2.2 Compatibility at the called terminal equipment. 44
6.3.10 Audiographic conference teleservice. 45
6.3.10.1 Codings required for the service specified in ETS 300 267 . 45
6.3.10.1.1 First connection. 45
6.3.10.1.2 Second connection . 47
6.3.10.2 Codings required for short term procedures . 48
6.3.10.2.1 Request by a calling terminal equipment . 49
6.3.10.2.2 Compatibility at the called terminal equipment. 50
6.3.11 Multimedia services . 51
6.3.11.1 Codings required for the service specified in F.700 . 51
6.3.11.1.1 First connection. 51
6.3.11.1.2 Second connection . 53
6.3.11.2 Codings required for short term procedures . 54
6.3.11.2.1 Request by a calling terminal equipment . 54
6.3.11.2.2 Compatibility at the called terminal equipment. 55
7 Coding examples applicable to specific user applications.56
7.1 Specific user applications of the circuit-mode 64 kbit/s unrestricted 8 kHz structured bearer service . 56
7.1.1 Support of terminal adapters V.110/X.30 . 56
7.1.1.1 Synchronous mode of operation . 56
7.1.1.1.1 Request by a calling terminal equipment . 56
7.1.1.1.2 Compatibility at the called terminal equipment. 57
7.1.1.2 Asynchronous mode of operation . 58
7.1.1.2.1 Request by a calling terminal equipment . 58
7.1.1.2.2 Compatibility at the called terminal equipment. 59
7.1.2 Support of X.25 terminal equipment allowing access to PSPDN via an access unit (ITU-T
Recommendation X.31, Case A) . 61
7.1.2.1 Rate adaption using X.31 HDLC flag stuffing. 61
7.1.2.1.1 Request by a calling terminal equipment . 61
7.1.2.1.2 Compatibility at the called terminal equipment. 62
ETSI
5 EG 201 018 V1.5.2 (1998-11)
7.1.2.2 Rate adaption corresponding to CCITT Recommendations V.110/X.30. 63
7.1.2.2.1 Request by a calling terminal equipment . 63
7.1.2.2.2 Compatibility at the called terminal equipment. 64
7.1.3 Support of teletex terminals using circuit-mode 64 kbit/s unrestricted 8 kHz-structured bearer
capability. 65
7.1.3.1 Request by a calling terminal equipment . 65
7.1.3.2 Compatibility at the called terminal equipment . 66
7.2 Specific user applications of the circuit mode 64 kbit/s 8 kHz structured bearer service category usable
for 3,1 kHz audio information transfer . 67
7.2.1 Voice band data via modem . 68
7.2.1.1 Request by a calling terminal equipment . 68
7.2.1.2 Compatibility at the called terminal equipment . 69
8 Interworking with non-European ISDNs supporting restricted 64 kbit/s transfer capability .70
8.1 Request by a calling terminal connected to a network supporting 64 kbit/s unrestricted digital
information transfer . 70
8.2 Compatibility at the called terminal equipment connected to a network supporting 64 kbit/s unrestricted
digital information transfer . 70
8.3 Request by a calling terminal connected to a non-European network supporting 64 kbit/s restricted
digital information transfer . 71
8.4 Compatibility at the called terminal equipment connected to a non-European network using restricted
digital information transfer . 71
9 Codings in the case where non-ISDNs are involved.72
9.1 Calls from PSTN to ISDN . 72
9.2 Calls from PSPDN to ISDN. 72
9.3 Calls from CSPDN to ISDN . 72
Annex A (informative): Bibliography.73
History.74
ETSI
6 EG 201 018 V1.5.2 (1998-11)
Intellectual Property Rights
IPRs essential or potentially essential to the present document may have been declared to ETSI. The information
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found
in SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in respect
of ETSI standards", which is available free of charge from the ETSI Secretariat. Latest updates are available on the
ETSI Web server (http://www.etsi.org/ipr).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee
can be given as to the existence of other IPRs not referenced in SR 000 314 (or the updates on the ETSI Web server)
which are, or may be, or may become, essential to the present document.
Foreword
This ETSI Guide (EG) has been produced by ETSI Technical Committee Signalling Protocols and Switching (SPS).
The present document replaces the fourth edition of ETR 018 issued in March 1995.
The following modifications have been made as compared to the fourth edition:
- examples of the use of the videoconferencing teleservice have been added (see subclause 6.3.9);
- examples of the use of the audiographic conferencing teleservice have been added (see subclause 6.3.10);
- examples of the use of multimedia services have been added (see subclause 6.3.11).
Further enhancements of the present document will (most likely) become necessary. Candidates for inclusion in a future
edition are e.g.:
- examples to document the user signalling bearer service;
- examples to document the teleaction teleservice;
- examples to support channel aggregation as an application of the 64 kbit/s unrestricted bearer service.
Introduction
The present document specifies the coding of the information elements Bearer Capability (BC), High Layer
Compatibility (HLC) and Low Layer Compatibility (LLC) to be used by terminals supporting the ISDN
telecommunication services so far specified within ETSI and operating in the demand mode. It is based on ITU-T
Recommendation Q.931 (1993) as modified by EN 300 403-1 [5], including its relevant annexes (B, I and J).
For each service it is specified which field values the calling user is requested to send and which field values the called
user could expect to receive in a pure ISDN environment (clauses 6 and 7). Clause 8 specifies the codings to be used in
the case of inter-working with non European ISDNs supporting restricted 64 kbit/s transfer capability. Furthermore,
interworking with the Public Switched Telephone Network (PSTN) is also covered (see subclause 9.1).
Unless otherwise stated, the use of the term "terminal" refers to customer's terminal apparatus which may be a Terminal
Equipment type 1 (TE1), a Terminal Adapter (TA) together with a Terminal Equipment type 2 (TE2) or a Network
Termination type 2 (NT2) as defined in ITU-T Recommendation I.411.
The terms "terminal" and "user" are used interchangeably.
ETSI
7 EG 201 018 V1.5.2 (1998-11)
The exact bit patterns correlated with the named field values can be found in the following subclauses of EN 300 403-
1 [5]:
- in subclause 4.5.5 for the bearer capability information element;
- in subclause 4.5.17 for the high layer compatibility information element; and
- in subclause 4.5.19 for the low layer compatibility information element.
Generally, the information elements BC, HLC and LLC serve the following purposes:
At the calling side, the network checks that the bearer service requested by the calling user in the bearer capability
information element matches with the bearer service provided to that user by the network (see EN 300 403-1 [5],
annex B).
At the called side, the called user performs network-to-user compatibility checking based on the content of the BC-
information element, and user-to-user compatibility checking based on the content of the HLC- and LLC- information
elements (see EN 300 403-1 [5], annex B).
ETSI
8 EG 201 018 V1.5.2 (1998-11)
1 Scope
The present document provides supplementary information on the usage of the compatibility information elements
Bearer Capability (BC), High Layer Compatibility (HLC) and Low Layer Compatibility (LLC) for individual
telecommunication services. It considers the telecommunications services as they are specified for public Integrated
Services Digital Networks (ISDNs). It does not specify additional codings of the compatibility information elements
which might be required to support the request and provision of telecommunication services by private networks.
Since some bearer services can be used to support various user applications, additional information on such applications
is specified:
- in subclause 7.1 for the circuit-mode 64 kbit/s unrestricted 8 kHz structured bearer service;
- in subclause 7.2 for the circuit-mode 64 kbit/s 8 kHz structured 3,1 kHz audio bearer service.
The specific objective of the present document is to provide guidance on the correct usage of EN 300 403-1 [5]
codepoints to the different ETSI Technical Committees or Technical Subcommittees dealing with services, ISDN
terminals, Terminal Adapters (TAs) and documents on testing. The present document shall help to assure inter-
operability of terminals supporting the same telecommunication service and shall enable terminals to operate on
different public ISDNs.
The typical codings specified in clause 6 should be supported by all users and networks supporting the corresponding
telecommunications service. Other variants of these codings may be supported in addition, however, these variants
might not provide for world-wide interoperability and might not guarantee terminal interchangeability.
The coding examples given in clause 7 are not exhaustive. They illustrate typical user applications involving bit rate
adaption schemes where ETSI standardized interfaces are used.
Clause 8 is devoted to examples showing the interworking of European ISDNs with non-European ISDNs supporting
restricted 64 kbit/s transfer capability.
Finally, clause 9 presents codings when interworking with non-ISDNs occurs.
2 References
References may be made to:
a) specific versions of publications (identified by date of publication, edition number, version number, etc.), in
which case, subsequent revisions to the referenced document do not apply; or
b) all versions up to and including the identified version (identified by "up to and including" before the version
identity); or
c) all versions subsequent to and including the identified version (identified by "onwards" following the version
identity); or
d) publications without mention of a specific version, in which case the latest version applies.
A non-specific reference to an ETS shall also be taken to refer to later versions published as an EN with the same
number.
[1] ETS 300 080: "Integrated Services Digital Network (ISDN); ISDN lower layer protocols for
telematic terminals".
[2] ETS 300 103 (1990): "Integrated Services Digital Network (ISDN); Support of
CCITT Recommendation X.21, X.21 bis and X.20 bis based Data Terminal Equipments (DTEs) by
an ISDN; Synchronous and asynchronous terminal adaption functions".
[3] ETS 300 218 (1993): "Integrated Services Digital Network (ISDN); Syntax-based videotex lower
layers protocols for ISDN packet mode (CCITT Recommendation X.31 Case A and Case B)".
ETSI
9 EG 201 018 V1.5.2 (1998-11)
[4] ETS 300 264 (1993): "Integrated Services Digital Network (ISDN); Videotelephony teleservice;
Service description".
[5] EN 300 403-1: "Integrated Services Digital Network (ISDN); Digital Subscriber Signalling System
No. one (DSS1) protocol; Signalling network layer for circuit-mode basic call control; Part 1:
Protocol specification [ITU-T Recommendation Q.931 (1993), modified]".
[6] ITU-T Recommendation F.184: "Operational provisions for the international public facsimile
service between subscriber stations with group 4 facsimile machines (telefax 4)".
[7] CCITT Recommendation F.200: "Teletex service".
[8] CCITT Recommendation F.220: "Service requirements unique to the processable mode number
one (PM1) used within the teletex service".
[9] CCITT Recommendation F.230: "Service requirements unique to the mixed mode (MM) used
within the teletex service".
[10] CCITT Recommendation T.90 (1992): "Characteristics and protocols for terminals for telematic
services in ISDN".
[11] CCITT Recommendation V.110 (1992): "Support of data terminal equipments with V-Series type
interfaces by an Integrated Services Digital Network (ISDN)".
[12] ITU-T 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".
[13] ITU-T Recommendation X.30 (1992): "Support of X.21, X.21 bis and X.20 bis based data
terminal equipments (DTEs) by an Integrated Services Digital Network (ISDN)".
[14] ITU-T Recommendation X.31 (1993): "Support of packet mode terminal equipment by an ISDN".
[15] ITU-T Recommendation X.75: "Packet-switched signalling system between public networks
providing data transmission services".
[16] ETS 300 383: "Integrated Services Digital Network (ISDN); File transfer over the ISDN-Eurofile
transfer profile".
[17] ETS 300 388: "Integrated Services Digital Network (ISDN); File Transfer & Access Management
(FTAM) over ISDN based on simple file transfer profile".
[18] ETS 300 267: "Integrated Services Digital Network (ISDN); Telephony 7 kHz, videotelephony,
audiographic conference and videoconference teleservices".
[19] ITU-T Recommendation F.700 (1996): "Framework recommendations for audiovisual/multimedia
services".
3 Abbreviations
For the purposes of the present document, the following abbreviations apply:
AU Access Unit
BC Bearer Capability
CSPDN Circuit Switched Public Data Network
HDLC High Level Data Link Control
HLC High Layer Compatibility
ISDN Integrated Services Digital Network
LLC Low Layer Compatibility
MSN Multiple Subscriber Number
NIC Network Independent Clock
NT Network Termination
PSPDN Packet Switched Public Data Network
ETSI
10 EG 201 018 V1.5.2 (1998-11)
PSTN Public Switched Telephone Network
SAPI Service Access Point Identifier
SUB Subaddressing
TA Terminal Adapter
TE Terminal Equipment
4 General principles applicable to all services
For all services, the following principles apply:
a) the LLC information element is transferred transparently through an ISDN between the calling entity and the
addressed entity. However, dependent on the charging principles applied, some networks may perform checks on
the length of the LLC information elements;
b) the HLC information element is transferred transparently through an ISDN between the calling entity and the
addressed entity. However, some networks may check its content, e.g., to associate a supplementary service to a
teleservice;
c) where bearer services are specified, the HLC information element will normally not be present unless they are
used to support high layer applications;
d) the coding examples consider the general case. In special terminal arrangements the user may need to rely on
address information only. In these cases the Multiple Subscriber Number (MSN) supplementary service shall be
used;
e) a Terminal Equipment type 2 (TE2) together with a TA are assumed to provide the same functionality as a
Terminal Equipment type 1 (TE1). Therefore, a TA should not generate and send a progress indicator when
setting-up a connection. Consequently, a TA, e.g., adapting a two-wire analogue Public Switched Telephone
Network (PSTN) user-network interface to the ISDN user-network interface will generate the BC and, if
appropriate, the HLC and LLC information elements in accordance with the type of equipment it serves at the
interface at the R reference point, namely:
BC-/HLC-/LLC-codepoints used at an interface at the coincident
Equipment connected to an interface S&T reference point
at the R reference point BC HLC LLC
analogue telephone speech telephony
facsimile group 2/3 equipment 3,1 kHz audio facsimile group 2/3
voice band data equipment via modem 3,1 kHz audio modem type
For the presentation of the coding examples, the following conventions apply:
- octets 1 and 2 of the compatibility information elements, indicating the information element identifier and length
respectively, are omitted from the considerations and therefore not shown in the examples;
- a dash instead of a field value indicates:
a) at the calling side: this field is not included in the information element;
b) at the called side: this field is not present;
- field values in brackets ( ) may or may not be included at the calling side and therefore not be present at the
called side.
ETSI
11 EG 201 018 V1.5.2 (1998-11)
5 Impact of interworking situations
5.1 Incoming calls from non-ISDNs
In the case of interworking with non-ISDNs, HLC and LLC information elements may be absent, and this interworking
is shown with the presence of the Progress indicator information element. When this occurs, the terminal should accept
the incoming call according to annex B of EN 300 403-1 [5], i.e. it should regard the compatibility as successful if it is
compatible with the included information, which as a minimum will be the Bearer capability information element.
5.2 BC and LLC application guidelines
In many cases, the same low layer information (e.g., the user rate and the rate adaption technique applied) can be coded
in either the BC or the LLC information element. However, the provision of information in the one or the other
information element has consequences with respect to the selection or the denial of a network provided interworking
function.
The following guidelines exist for the application of BC and LLC information elements according to annex I of EN 300
403-1 [5]:
Type I Information used only at the destination end to allow decision regarding terminal compatibility. This
information, if required, shall be coded into octets (3a and) 5 to 7 of the LLC information element.
Type II Information to permit the network to select the bearer service. This information shall be coded into:
- octets 3 and 4 of the BC information element for circuit-mode traffic;
- octets 3 and 4, 6 and 7 of the BC information element for packet-mode traffic.
Type III Information used by the addressed user to determine terminal compatibility and used by the network to
facilitate interworking with other ISDNs or other dedicated networks. This information is encoded into
octet 5 (including octets 5a-5d if appropriate) of the BC information element.
These types of information can be used as follows:
Case 1 If the originating user wishes to transfer information end-to-end to ensure end user compatibility without
invoking network interworking, then type I information together with type II information shall apply.
Case 2 If the originating user either requires network interworking or is willing to accept network interworking,
should it be necessary in order to complete the call, then type III information together with type II
information shall apply.
Consequently, if interworking with a PSTN, Circuit Switched Public Data Network (CSPDN) or the pan-European
mobile cellular system is supported by the network by providing the appropriate functions (i.e. data extraction, modem
pool) at the interworking unit, then those calls carrying the rate adaption information in the LLC information element
may not be successfully completed. These calls will be successful instead, when the rate adaption information is
included in the BC information element.
Terminals shall have the capability to determine compatibility independent of whether the compatibility information is
coded in the BC information element (as type III information) or in the LLC information element (as type I information).
ETSI
12 EG 201 018 V1.5.2 (1998-11)
6 Request and recognition of a basic
telecommunication service in an ISDN environment
The examples given in this clause assume that a pure ISDN environment exists and no network-provided interworking
function is selected.
Therefore, the particular user rate as well as the rate adaption technique applied are specified in the LLC information
element, thus permitting compatibility decision by the destination terminal.
6.1 Request and recognition of a circuit-mode bearer service
6.1.1 Circuit-mode 64 kbit/s 8 kHz structured bearer service category
usable for speech information transfer
6.1.1.1 Request by a calling terminal equipment
a) Bearer capability information element coding:
Octet Information element field Field value
3 Coding standard CCITT standardized coding
Information transfer capability speech
4 Transfer mode circuit mode
Information transfer rate 64 kbit/s
5 User information layer 1 protocol Recommendation G.711, A-law
6 User information layer 2 protocol ———
7 User information layer 3 protocol ———
b) High layer compatibility information element coding:
This information element shall not be included.
c) Low layer compatibility information element coding:
This information element is not required.
6.1.1.2 Compatibility at the called terminal equipment
a) Bearer capability information element coding:
Octet Information element field Field value
3 Coding standard CCITT standardized coding
Information transfer capability speech
4 Transfer mode circuit mode
Information transfer rate 64 kbit/s
5 User information layer 1 protocol Recommendation G.711, A-law
6 User information layer 2 protocol ———
7 User information layer 3 protocol ———
b) High layer compatibility information element coding:
Terminals supporting circuit-mode 64 kbit/s 8 kHz structured speech bearer service shall be able to accept
incoming calls from terminals which include the HLC information element (see subclause 6.3.1.2). If an HLC
information element for telephony is received and the terminal supports HLC analysis, it shall consider the
compatibility check to be successful if the HLC information element is coded as specified in subclause 6.3.1.2).
If an HLC information element is not received, the call shall be accepted if the compatibility checks on the BC
and LLC information element (if present) are successful.
ETSI
13 EG 201 018 V1.5.2 (1998-11)
c) Low layer compatibility information element coding:
This information element is normally absent. If present, it may be used for compatibility checking or be ignored
by the terminal. If any conflict from duplication of the information in the BC and LLC information elements is
detected, the conflict shall be resolved in favour of the BC information element, i.e., the conflicting information
in the LLC information element shall be ignored.
6.1.2 Circuit-mode 64 kbit/s unrestricted 8 kHz structured bearer service
category
More specific user applications of this bearer service can be found in clause 7.
Interworking with networks using restricted digital information transfer is covered in clause 8.
6.1.2.1 Request by a calling terminal equipment
a) Bearer capability information element coding:
Octet Information element field Field value
3 Coding standard CCITT standardized coding
Information transfer capability unrestricted digital information
4 Transfer mode circuit mode
Information transfer rate 64 kbit/s
5 User information layer 1 protocol ———
6 User information layer 2 protocol ———
7 User information layer 3 protocol ———
b) High layer compatibility information element coding:
This information element is optional. If present, it shall be encoded in accordance with EN 300 403-1 [5],
subclause 4.5.17.
c) Low layer compatibility information element coding:
This information element is optional. If present, it shall be encoded in accordance with EN 300 403-1 [5],
subclause 4.5.19.
6.1.2.2 Compatibility at the called terminal equipment
a) Bearer capability information element coding:
Octet Information element field Field value
3 Coding standard CCITT standardized coding
Information transfer capability unrestricted digital information
4 Transfer mode circuit mode
Information transfer rate 64 kbit/s
5 User information layer 1 protocol ———
6 User information layer 2 protocol ———
7 User information layer 3 protocol ———
b) High layer compatibility information element coding:
This information element is present if provided by the calling user. If present, it is checked for terminal
compatibility according to annex B of EN 300 403-1 [5].
c) Low layer compatibility information element coding:
This information element is present if provided by the calling user. If present, it is checked for terminal
compatibility according to annex B of EN 300 403-1 [5] and for parameter negotiation according to annex J of
EN 300 403-1 [5].
ETSI
14 EG 201 018 V1.5.2 (1998-11)
6.1.3 Circuit-mode 64 kbit/s 8 kHz structured bearer service category
usable for 3,1 kHz audio information transfer
More specific user applications of this bearer service can be found in clause 7.
6.1.3.1 Request by a calling terminal equipment
a) Bearer capability information element coding:
Octet Information element field Field value
3 Coding standard CCITT standardized coding
Information transfer capability 3,1 kHz audio
4 Transfer mode circuit mode
Information transfer rate 64 kbit/s
5 User information layer 1 protocol Recommendation G.711, A-law
6 User information layer 2 protocol ———
7 User information layer 3 protocol ———
b) High layer compatibility information element coding:
This information element is optional. If present, it shall be encoded in accordance with EN 300 403-1 [5],
subclause 4.5.17.
c) Low layer compatibility information element coding:
This information element is optional. If present, it shall be encoded in accordance with EN 300 403-1 [5],
subclause 4.5.19.
6.1.3.2 Compatibility at the called terminal equipment
a) Bearer capability inform
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