SIST ETS 300 136 E1:2003

• Abstract:

  T/NA1(89)21

• Status: Published
• Publication Date: 30-Nov-2003
• 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 300 136 ed.1 (1992-03) - Integrated Services Digital Network (ISDN); Closed User Group (CUG) supplementary service; Service description

Overview

SIST ETS 300 136 E1:2003 defines the Closed User Group (CUG) supplementary service within the Integrated Services Digital Network (ISDN) framework. Standardized by SIST and technically equivalent to ETS 300 136 Edition 1, this document outlines the principles, user requirements, and service description for CUGs in public and private ISDNs as applied by European telecommunications operators.

The primary goal of the CUG supplementary service is to enable users or groups of subscribers to restrict communication to a defined group, thus enhancing network security, privacy, and organizational control within ISDN-based digital telecommunications environments.

Key Topics

• Closed User Group (CUG) Principles

  • Membership allows restricted communication in both directions within groups.
  • Users may belong to multiple CUGs and can be assigned specific access controls for incoming or outgoing calls.
  • Group identity is managed via unique indices allocated by the network and is applied either to all or selected basic services.

• Service Features and Options

  • Access Capabilities: Subscribers can configure incoming/outgoing call permissions both inside and outside the group.
  • Preferential CUG: A default group can be designated for automatic invocation unless another is specified by the user.
  • Subscription Management: Network operators handle provisioning, modification, and withdrawal of CUG arrangements upon user request.
  • Group Communication Rules: Calls within the CUG or to outside parties are subject to predefined restrictions and network validation.

• Interworking and Compatibility

  • Supports interoperability between public and private ISDNs.
  • Ensures proper group management when spanning multiple network types.
  • Interaction with non-ISDN networks is addressed at the interconnection level.

• Interaction with Other Supplementary Services

  • CUG is designed to coexist with other ISDN supplementary features like call transfer, call forwarding, conference calls, multiple subscriber numbers, and user-to-user signaling.
  • The standard details scenarios where CUG requirements must be maintained, particularly for features like call transfer and forwarding, to prevent circumvention of group restrictions.

Applications

The CUG supplementary service is crucial in areas where controlled group communications are necessary:

• Corporate Telecommunication Networks:
  Enables teams, departments, and business units to communicate securely within their defined groups, restricting unwanted access and ensuring privacy.

• Government and Public Sector Operations:
  Public administration entities and emergency services benefit from isolated communication groups to support mission-critical activities.

• Service Providers and Large Enterprises:
  Organizations with complex internal structures or subsidiaries can apply CUGs to manage intra-organizational communication policies over ISDN.

• Private Branch Exchange (PBX) and Virtual Network Management:
  Integrates with PBX solutions to mirror organizational hierarchies on the ISDN level, enforcing group-based calling privileges.

Related Standards

• ETS 300 137, ETS 300 138
  Define subsequent implementation layers: functional capabilities, signaling, and switching for CUG within ISDN environments.

• CCITT Recommendations:

  • I.130: Service characterization methodology.
  • I.112, I.210: Fundamental vocabulary and service principles for ISDN.
  • E.164: Numbering plan relevant to ISDN.
  • X.180: Administrative aspects of international CUGs.
  • Q.9: Switching and signaling vocabulary.

• ETS 300 089
  Covers related supplementary services such as Calling Line Identification Presentation (CLIP).

By adhering to SIST ETS 300 136 E1:2003, service providers ensure secure, scalable, and standardized management of controlled communications within ISDN, supporting both operational needs and regulatory requirements in digital telecommunications.

SLOVENSKI STANDARD
01-december-2003
Digitalno omrežje z integriranimi storitvami (ISDN) – Dopolnilna storitev: zaprta
skupina uporabnikov (CUG) – Opis storitve
Integrated Services Digital Network (ISDN); Closed User Group (CUG) supplementary
service; Service description
Ta slovenski standard je istoveten z: ETS 300 136 Edition 1
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.

EUROPEAN ETS 300 136
TELECOMMUNICATION March 1992
STANDARD
Source: ETSI TC-NA Reference: T/NA1(89)21
ICS: 33.080
ISDN, supplementary service
Key words:
Integrated Services Digital Network (ISDN);
Closed User Group (CUG) supplementary service
Service description
ETSI
European Telecommunications Standards Institute
ETSI Secretariat
F-06921 Sophia Antipolis CEDEX - FRANCE
Postal address:
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 1992. All rights reserved.
New presentation - see History box

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ETS 300 136: March 1992
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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ETS 300 136: March 1992
Contents
Foreword.5
1 Scope .7
2 Normative references .7
3 Definitions.8
4 Symbols and abbreviations.9
5 Description .9
6 Procedures.9
6.1 Provision and withdrawal .9
6.2 Normal procedures.10
6.2.1 Activation, deactivation and registration.10
6.2.2 Erasure . 11
6.2.3 Invocation and operation .11
6.2.3.1 Originating calls.11
6.2.3.1.1 Preferential closed user group without outgoing access
capability .11
6.2.3.1.2 Outgoing access capability without preferential closed
user group .11
6.2.3.1.3 Both preferential closed user group and outgoing access
capability .11
6.2.3.2 Terminating calls.11
6.2.4 Interrogation .12
6.3 Exceptional procedures .12
6.3.1 Activation, deactivation and registration.12
6.3.2 Erasure . 12
6.3.3 Invocation and operation .13
6.3.4 Interrogation .13
7 Intercommunication considerations.13
7.1 Interworking with non-ISDNs.13
7.2 Interworking with private ISDNs.13
8 Interaction with other supplementary services.14
8.1 Advice of charge services .14
8.1.1 Charging information at call setup time.14
8.1.2 Charging information during the call.14
8.1.3 Charging information at the end of the call.14
8.2 Call waiting.14
8.3 Call hold.14
8.4 Call transfer services. 14
8.4.1 Explicit call transfer .14
8.4.2 Single step call transfer .14
8.5 Number identification services .15
8.5.1 Calling line identification presentation .15
8.5.2 Calling line identification restriction.15
8.5.3 Connected line identification presentation .15
8.5.4 Connected line identification restriction.15
8.6 Closed user group.15
8.7 Completion of calls to busy subscriber.15

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ETS 300 136: March 1992
8.8 Conference services.15
8.8.1 Conference call, add-on .15
8.8.2 Meet-me conference.15
8.9 Direct dialling in.15
8.10 Diversion services .16
8.10.1 Call forwarding unconditional .16
8.10.2 Call forwarding busy .16
8.10.3 Call forwarding no reply .16
8.10.4 Call deflection .16
8.11 Freephone.16
8.12 Malicious call identification .16
8.13 Multiple subscriber number.17
8.14 Subaddressing.17
8.15 Terminal portability .17
8.16 Three party.17
8.17 User-to-user signalIing.17
History .18

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ETS 300 136: March 1992
Foreword
This European Telecommunication Standard (ETS) has been produced by the Network Aspects (NA)
Technical Committee of the European Telecommunications Standards Institute (ETSI).
In accordance with CCITT Recommendation I.130 [1], the following three level structure is used to
describe the supplementary telecommunications services as provided by European public
telecommunications operators under the pan-European Integrated Services Digital Network (ISDN):
- Stage 1: is an overall service description, from the user's standpoint;
- Stage 2: identifies the functional capabilities and information flows needed to support the service
described in stage 1; and
- Stage 3: defines the signalling system protocols and switching functions needed to implement the
service described in stage 1.
This standard details the stage 1 aspects (overall service description) for the Closed User Group (CUG)
supplementary service. The stage 2 and stage 3 aspects are detailed in ETS 300 137 (1992) and
ETS 300 138 (1992), respectively.

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Blank page
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1 Scope
This standard defines the stage one of the Closed User Group (CUG) supplementary service for the pan-
European Integrated Services Digital Network (ISDN) as provided by European public telecommunications
operators. Stage one is an overall service description from the user's point of view (see CCITT
Recommendation I.130 [1]), but does not deal with the details of the human interface itself.
This standard defines the interworking requirements of private ISDNs with the public ISDN.
In addition this standard specifies the base functionality where the service is provided to the user via a
private ISDN.
This standard does not specify the additional requirements where the service is provided to the user via a
telecommunications network that is not an ISDN, but it does include interworking requirements of other
networks with the public ISDN.
Interactions with supplementary services not listed in Clause 8 are outside the scope of this standard.
Charging principles are outside the scope of this standard.
The CUG supplementary service enables users to form groups to and from which access is restricted. A
specific user may be a member of one or more closed user groups. Members of a specific closed user
group can communicate among each other but not, in general, with users outside the group.
Some networks may permit closed user group members to make special calls which are outside that
user's closed user group requirements (e.g., calls to emergency services). This functionality and
associated procedures are outside the scope of this standard.
The CUG supplementary service is applicable to all telecommunications services.
This standard is applicable to the stage two and stage three standards for the ISDN CUG supplementary
service. The terms "stage two" and "stage three" are also defined in CCITT Recommendation I.130 [1].
Where the text indicates the status of a requirement (i.e. as strict command or prohibition, as authorisation
leaving freedom, or as a capability or possibility), this shall be reflected in the text of the relevant stage
two and stage three standards.
Furthermore, conformance to this standard is met by conforming to the stage three standards with the field
of application appropriate to the equipment being implemented. Therefore no method of testing is provided
for this standard.
2 Normative references
This ETS incorporates, by dated or 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] CCITT Recommendation I.130 (1988): "Method for the characterisation of
telecommunication services supported by an ISDN and network capabilities of an
ISDN".
[2] CCITT Recommendation I.112 (1988): "Vocabulary of terms for ISDNs".
[3] CCITT Recommendation I.210 (1988): "Principles of telecommunication services
supported by an ISDN and the means used to describe them".

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ETS 300 136: March 1992
[4] CCITT Recommendation E.164 (1988): "Numbering plan for the ISDN era".
[5] CCITT Recommendation X.180 (1988): "Administrative arrangements for
international closed user groups".
[6] CCITT Recommendation Q.9 (1988): "Vocabulary of switching and signalling
terms".
[7] ETS 300 089 (1992): "Integrated Services DIgital Network (ISDN); Calling Line
Identification Presentation (CLIP) supplementary service; Service description".
3 Definitions
For the purposes of this standard the following definitions apply:
Integrated Services Digital Network (ISDN): see CCITT Recommendation I.112 [2], § 2.3, definition
308.
(Basic) service; telecommunications service: see CCITT Recommendation I.112 [2], § 2.2, definition
201.
Supplementary service: see CCITT Recommendation I.210 [3], § 2.4.
ISDN number: a number conforming to the numbering plan and structure specified in CCITT
Recommendation E.164 [4].
Closed user group (CUG) member: a user who has subscribed to the CUG supplementary service and is
one of the users in the group formed by a particular closed user group.
Closed user group (CUG) index: a value assigned by the network to identify a closed user group. This
value is used in closed user group calls at the user's access.
Preferential CUG: a preferential closed user group is the nominated default group to be used when no
closed user group or explicit outgoing access request is received by the network.
Incoming access: an arrangement which allows a member of a closed user group to receive calls from
outside the closed user group.
Outgoing access: an arrangement which allows a member of a closed user group to place calls outside
the closed user group.
Incoming calls barred within a closed user group: an access restriction that prevents a closed user
group member from receiving calls from other members of that group.
Outgoing calls barred within a closed user group: an access restriction that prevents a closed user
group member from placing calls to other members of that group.
Closed user group call: a closed user group call is a call which is restricted to a pre-defined group of
users.
Basic access: see CCITT Recommendation Q.9 [6], § 1, definition 1551.
Primary rate access: see CCITT Recommendation Q.9 [6], § 1, definition 1552.

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ETS 300 136: March 1992
4 Symbols and abbreviations
CUG Closed User Group
ISDN Integrated Services Digital Network
PSTN Public Switched Telephone Network
5 Description
The CUG supplementary service shall apply to the basic access and to the primary rate access.
The CUG supplementary service enables users to form groups to and from which access is restricted. A
specific user may be a member of one or more closed user groups. Members of a specific closed user
group can communicate among each other but not, in general, with users outside the group.
A closed user group consists of a number of users. A closed user group can have members from one or
more public networks. In the ISDN, each member of a closed user group is identified by their ISDN number
(see also subclauses 8.9 and 8.13).
Subscription to a closed user group shall be defined for all basic services, or in relation to one, or to a list
of basic services.
Closed user group members can have additional capabilities that allow them to originate calls outside the
group, and/or to receive calls from outside the group. Closed user group members can have additional
restrictions that prevent them from originating calls to other members of the closed user group, or from
receiving calls from other members of the closed user group.
6 Procedures
6.1 Provision and withdrawal
The CUG supplementary service shall be provided after prior arrangement with the service provider.
As a network option, the CUG supplementary service can be offered with several subscription options. For
a particular closed user group, the associated set of general subscription options can apply to one basic
service, to a particular set of basic services, or to all basic services (see table 1A).
A user may subscribe to one of two additional restrictions applying to each particular closed user group:
- incoming calls barred within a closed user group;
- outgoing calls barred within a closed user group.
A user can be a member of several closed user groups. Each network operator shall define the maximum
number of closed user groups which can be allocated to an individual user.
When a user subscribes to the CUG supplementary service, a network operator shall also register one of
the following service arrangements as requested by the user (see table 1B):
- closed user group calls only;
- closed user group with incoming access, i.e. can also receive calls which are not subject to closed
user group restrictions; or
- closed user group with outgoing access, i.e. can also make calls which are not subject to closed
user group restrictions; or
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ETS 300 136: March 1992
- closed user group with incoming and outgoing access, i.e. can also make and receive calls which
are not subject to closed user group restrictions.
The network shall provide a subscription option in order to enable the user to specify a preferential closed
user group (see table 1B). The user can reques
...