ETSI EN 300 138-1 V1.3.4 (1998-06)

SLOVENSKI STANDARD
01-april-2005
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Integrated Services Digital Network (ISDN); Closed User Group (CUG) supplementary
service; Digital Subscriber Signalling System No. one (DSS1) protocol; Part 1: Protocol
specification
Ta slovenski standard je istoveten z: EN 300 138-1 Version 1.3.4
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.

EN 300 138-1 V1.3.4 (1998-06)
European Standard (Telecommunications series)
Integrated Services Digital Network (ISDN);
Closed User Group (CUG) supplementary service;
Digital Subscriber Signalling System No. one (DSS1) protocol;
Part 1: Protocol specification

2 EN 300 138-1 V1.3.4 (1998-06)
Reference
REN/SPS-05145-H-1 (1a090j2o.PDF)
Keywords
ISDN, CUG, DSS1, supplementary service
ETSI
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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 1998.
All rights reserved.
ETSI
3 EN 300 138-1 V1.3.4 (1998-06)
Contents
Intellectual Property Rights. 5
Foreword. 5
1 Scope . 7
2 Normative references. 7
3 Definitions. 8
4 Abbreviations.9
5 Description . 9
6 Operational requirements . 9
6.1 Provision and withdrawal.9
6.2 Requirements on the originating network side.10
6.3 Requirements on the destination network side .10
7 Coding requirements. 10
7.1 ASN.1 description of coding requirements .10
7.2 Coding of the Cause information element.11
8 State definitions. 12
9 Signalling procedures at the coincident S and T reference point . 12
9.1 Activation, deactivation and registration .12
9.2 Invocation and operation.12
9.2.1 Call originating from a user with the CUG supplementary service (explicit request).12
9.2.1.1 Normal operation.12
9.2.1.2 Exceptional procedures .13
9.2.2 Call originating from a user with the CUG supplementary service (default request).13
9.2.2.1 Normal operation.13
9.2.2.2 Exceptional procedures .13
9.2.3 Call originating from a user without the CUG supplementary service.14
9.2.3.1 Normal operation.14
9.2.3.2 Exceptional procedures .14
9.2.4 Call terminating at a user with the CUG supplementary service.14
9.2.4.1 Normal operation.14
9.2.4.2 Exceptional procedures .15
9.2.5 CUG checks at the originating and destination network.16
10 Procedures for interworking with private ISDNs . 17
11 Interactions with other networks. 17
12 Interactions with other supplementary services. 17
13 Parameter values (timers). 17
14 Dynamic description (SDL diagrams). 18
14.1 The CUG process.18
14.2 Relation to basic call control.18
ETSI
4 EN 300 138-1 V1.3.4 (1998-06)
Annex A (informative): Signalling flows . 23
Annex B (informative): Diagram description of coding requirements. 25
B.1 CUG call invoke component (typical example). 25
B.2 CUG call return error component. 26
Annex C (normative): Mapping of return errors and cause values. 27
C.1 Mapping at the destination network side. 27
C.2 Mapping at the originating network side . 28
Annex D (informative): Changes with respect to the previous ETS 300 138-1 . 29
Annex E (informative): Bibliography. 30
History. 31
ETSI
5 EN 300 138-1 V1.3.4 (1998-06)
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.fr/ipr or 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 European Standard (Telecommunications series) has been produced by ETSI Technical Committee Signalling
Protocols and Switching (SPS).
The present document is part 1 of a multi-part standard covering the Digital Subscriber Signalling System No. one (DSS1)
protocol specification for the Integrated Services Digital Network (ISDN) Closed User Group (CUG) supplementary
service, as described below:
Part 1: "Protocol specification";
Part 2: "Protocol Implementation Conformance Statement (PICS) proforma specification";
Part 3: "Test Suite Structure and Test Purposes (TSS&TP) specification for the user";
Part 4: "Abstract Test Suite (ATS) and partial Protocol Implementation eXtra Information for Testing (PIXIT)
proforma specification for the user";
Part 5: "Test Suite Structure and Test Purposes (TSS&TP) specification for the network";
Part 6: "Abstract Test Suite (ATS) and partial Protocol Implementation eXtra Information for Testing (PIXIT)
proforma specification for the network".
In accordance with CCITT Recommendation I.130, the following three level structure is used to describe the
supplementary telecommunication 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 stand-point;
- 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.
The present document details the stage 3 aspects (signalling system protocols and switching functions) needed to support
the CUG supplementary service. The stage 1 and stage 2 aspects are detailed in ETS 300 136 and ETS 300 137,
respectively.
The present version updates the references to the basic call specifications.
ETSI
6 EN 300 138-1 V1.3.4 (1998-06)
National transposition dates
Date of adoption of this EN: 19 June 1998
Date of latest announcement of this EN (doa): 30 September 1998
Date of latest publication of new National Standard
or endorsement of this EN (dop/e): 31 March 1999
Date of withdrawal of any conflicting National Standard (dow): 31 March 1999
ETSI
7 EN 300 138-1 V1.3.4 (1998-06)
1 Scope
This first part of EN 300 138 specifies the stage three of the Closed User Group (CUG) supplementary service for the
pan-European Integrated Services Digital Network (ISDN) as provided by European public telecommunications operators
at the T reference point or coincident S and T reference point (as defined in ITU-T Recommendation I.411 [5]) by means
of the Digital Subscriber Signalling System No. one (DSS1) protocol. Stage three identifies the protocol procedures and
switching functions needed to support a telecommunication service (see CCITT Recommendation I.130 [3]).
In addition, the present document specifies the protocol requirements at the T reference point where the service is
provided to the user via a private ISDN.
The present document does not specify the additional protocol requirements where the service is provided to the user via
a telecommunications network that is not an ISDN.
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 CUGs. Members of a specific CUG can communicate among themselves but not, in general,
with users outside the group.
The CUG supplementary service is applicable to all telecommunication services.
Further parts of this EN specify the method of testing required to identify conformance to the present document.
The present document is applicable to equipment, supporting the CUG supplementary service, to be attached at either side
of a T reference point or coincident S and T reference points when used as an access to the public ISDN.
2 Normative 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] CCITT Recommendation E.164: "Numbering plan for the ISDN era".
[2] ITU-T Recommendation I.112: "Vocabulary of terms for ISDNs".
[3] CCITT Recommendation I.130 (1988): "Method for the characterization of telecommunication
services supported by an ISDN and network capabilities of an ISDN".
[4] ITU-T Recommendation I.210: "Principles of telecommunication services supported by an ISDN
and the means used to describe them".
[5] ITU-T Recommendation I.411 (1993): "ISDN user-network interfaces - Reference configurations".
[6] CCITT Recommendation X.208 (1988): "Open Systems Interconnection (OSI); Model and Notation:
Service definition: Specification of Abstract Syntax Notation One (ASN.1)".
[7] CCITT Recommendation X.209 (1988): "Open Systems Interconnection (OSI); Model and Notation:
Service definition: Specification of basic encoding rules for Abstract Syntax Notation One
(ASN.1)".
[8] CCITT Recommendation X.219 (1988): "Remote Operations: Notation and Service Definition".
ETSI
8 EN 300 138-1 V1.3.4 (1998-06)
[9] CCITT Recommendation Z.100 (1988): "Functional Specification and Description Language
(SDL)".
[10] ETS 300 136 (1992): "Integrated Services Digital Network (ISDN); Closed User Group (CUG)
supplementary service; Service description".
[11] EN 300 195-1: "Integrated Services Digital Network (ISDN); Supplementary service interactions;
Digital Subscriber Signalling System No. one (DSS1) protocol; Part 1: Protocol specification".
[12] EN 300 196-1: "Integrated Services Digital Network (ISDN); Generic functional protocol for the
support of supplementary services; Digital Subscriber Signalling System No. one (DSS1) protocol;
Part 1: Protocol specification".
[13] 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]".
[14] EN 300 403-2: "Integrated Services Digital Network (ISDN); Digital Subscriber Signalling System
No. one (DSS1) protocol; Signalling network layer for circuit-mode basic call control; Part 2:
Specification and Description Language (SDL) diagrams".
[15] EN 300 485: "Integrated Services Digital Network (ISDN); Definition and usage of cause and
location in Digital Subscriber Signalling System No. one (DSS1) and Signalling System No.7 ISDN
User Part (ISUP) [ITU-T Recommendation Q.850 (1993), modified]".
3 Definitions
For the purposes of the present document, the following definitions apply:
basic telecommunication service: A bearer service or teleservice. The terms "bearer service" and "teleservice" are
defined in ITU-T Recommendation I.112 [2], definitions 202 and 203.
CUG call: See ETS 300 136 [10], clause 3.
CUG index: The CUG index is a parameter used by the calling user to select a particular CUG when originating a call.
The index is also used by the network to indicate to the called user the CUG from which an incoming call has originated.
This index has only local significance, i.e. the index used by the calling user is, in general, different from the index used
by the called user to identify the same CUG.
CUG interlock code: This is a means of identifying CUG membership within the network. At the calling side, if a CUG
match exists, the CUG index identifying a CUG maps to the CUG interlock code for that CUG. If a CUG match exists at the
called side the CUG interlock code identifying a CUG maps to the CUG index representing that CUG. CUG interlock code
is not an access concept, but is used for clarity during the descriptions of signalling procedures and flows.
default number: An agreed ISDN number between the user at the calling side and the network provider.
incoming access: See ETS 300 136 [10], clause 3.
incoming calls barred within a CUG: See ETS 300 136 [10], clause 3.
Integrated Services Digital Network (ISDN): See ITU-T Recommendation I.112 [2], definition 308.
ISDN number: A number conforming to the numbering plan and structure specified in CCITT Recommendation E.164 [1].
network: The DSS1 protocol entity at the network side of the user-network interface.
outgoing access: See ETS 300 136 [10], clause 3.
outgoing calls barred within a CUG: See ETS 300 136 [10], clause 3.
preferential CUG: A CUG user subscribing to preferential CUG nominates a CUG index which the network uses as a
default to identify the required CUG in the absence of any CUG information in the outgoing call request. A preferential
CUG applies to an ISDN number (or to an ISDN number/service - see subclause 6.1) and not to a specific CUG.
ETSI
9 EN 300 138-1 V1.3.4 (1998-06)
service; telecommunication service: See ITU-T Recommendation I.112 [2], definition 201.
supplementary service: See ITU-T Recommendation I.210 [4], subclause 2.4.
user: The DSS1 protocol entity at the user side of the user-network interface.
4 Abbreviations
For the purposes of the present document, the following abbreviations apply:
CES Connection Endpoint Suffix
CUG Closed User Group
DSS1 Digital Subscriber Signalling System No. one
IA Incoming Access
ICB Incoming Calls Barred within a CUG
ISDN Integrated Services Digital Network
ISUP Integrated Services User Part
OA Outgoing Access
OCB Outgoing Calls Barred within a CUG
SDL Specification and Description Language
5 Description
Essentially normal call establishment procedures shall apply but, additionally, to provide the CUG supplementary
service, the network shall analyse the call request from the calling user in conjunction with the CUG attributes associated
with both the calling and called users (as identified by their ISDN numbers). As a result of this analysis the call can either
fail for CUG supplementary service reasons or be allowed to proceed.
The network provider may define the maximum number of CUGs of which a user can be a member.
Since the fundamental purpose of the CUG supplementary service is to prevent certain connections the network shall
strictly control interactions with some other supplementary services to protect CUG integrity.
6 Operational requirements
6.1 Provision and withdrawal
The provision of the CUG supplementary service to a new member and also the assignment of the various CUG
supplementary service options to a new or existing member, shall require a prior arrangement between the member and
the network provider.
The CUG supplementary service shall be provided on a subscription basis. As a network provider option, the CUG
supplementary service may be offered with subscription options.
The options can be divided into two groups:
a) the options shown in table 1 shall apply per ISDN number. The option values may be assigned individually for
each basic service, or set of basic services, available at the ISDN number with the CUG supplementary service;
b) the option shown in table 2 shall apply per CUG provided at the ISDN number with the CUG supplementary
service.
ETSI
10 EN 300 138-1 V1.3.4 (1998-06)
Table 1: Options available per ISDN number
Option (note) Values
1) Preferential CUG Nominated CUG index, or none designated.
2) Outgoing access Allowed, or not allowed.
3) Incoming access Allowed, or not allowed.
NOTE: If, for a user with the CUG supplementary service, a basic service, or set of basic services, is not included
in at least one CUG, then:
- preferential CUG shall have the "none designated" option value;
- outgoing access shall have the "allowed" option value if normal outgoing calls using that basic service,
or set of basic services, are required;
- incoming access shall have the "allowed" option value if incoming calls using that basic service, or set
of basic services, are required.
Table 2: Options available per CUG
Option Values
1) Barring within the CUG None, incoming calls, or outgoing calls.
The options assigned to a CUG member shall be stored in the network.
Withdrawal of the CUG supplementary service shall be as a result of network provider action either at the request of a
particular member, or for administrative reasons.
6.2 Requirements on the originating network side
For correct interactions with certain other supplementary services, the originating network side shall store, for the
duration of the call, details of whether a normal or a CUG call was requested in the information sent to the destination
network side. The CUG interlock code (if any) of the call request to the destination network side shall also be retained.
However, if the network knows that such interactions are not possible (e.g. the user has only the CUG supplementary
service) then the information may be discarded.
6.3 Requirements on the destination network side
For correct interactions with certain other supplementary services, the destination network side shall store, for the
duration of the call, details of whether a normal or a CUG call request was passed to the called user. The CUG interlock
code (if any) of the call request shall also be retained. However, if the network knows that such interactions are not
possible (e.g. the user has only the CUG supplementary service) then the information may be discarded.
7 Coding requirements
7.1 ASN.1 description of coding requirements
Table 3 provides an Abstract Syntax Notation one (ASN.1) description of the coding of the Facility information element
components necessary to support this service in accordance with CCITT Recommendations X.208 [6] and X.209 [7] and
uses the OPERATION and ERROR macro as defined in figure 4/X.219 of CCITT Recommendation X.219 [8].
ETSI
11 EN 300 138-1 V1.3.4 (1998-06)
Table 3: Definition of operations and errors for the CUG supplementary service
Closed-User-Group-Service-Operations {ccitt identified-organization etsi(0) 138
operations-and-errors (1)}
DEFINITION ::=
BEGIN
EXPORTS CUGCall,
InvalidOrUnregisteredCUGIndex,
RequestedBasicServiceViolatesCUGConstraints,
OutgoingCallsBarredWithinCUG,
IncomingCallsBarredWithinCUG,
UserNotMemeberOfCUG,
InconsistencyInDesignatedFacilityAndSubscriberClass
IMPORTS OPERATION,
ERROR
FROM Remote-Operation-Notation
{joint-iso-ccitt remote-operations(4) notation(0)}
notSubscribed,
basicServiceNotProvided
FROM General-Errors
{ccitt identified-organization etsi(0) 196 general-errors}
;
CUGcall ::= OPERATION
-- in Facility information element. Invoked from calling user to originating
-- network side. Also from destination network side to called user
ARGUMENT SEQUENCE {
OARequested DEFAULT FALSE,
CUGIndex OPTIONAL}
-- in SETUP message
ERRORS {
invalidOrUnregisteredCUGIndex,
requestedBasicServiceViolatesCUGConstraints,
outgoingCallsBarredWithinCUG,
incomingCallsBarredWithinCUG,
userNotMemberOfCUG,
basicServiceNotProvided,
inconsistencyInDesignatedFacilityAndSubscriberClass,
notSubscribed
}
-- in clearing message to calling user. Also to destination network side.
OARequested ::= [1] IMPLICIT BOOLEAN
CUGIndex ::= [2] IMPLICIT INTEGER (0.32767)
InvalidOrUnregisteredCUGIndex ::= ERROR
RequestedBasicServiceViolatesCUGConstraints ::= ERROR
OutgoingCallsBarredWithinCUG ::= ERROR
IncomingCallsBarredWithinCUG ::= ERROR
UserNotMemberOfCUG ::= ERROR
InconsistencyInDesignatedFacilityAndSubscriberClass ::= ERROR
cUGCall CUGCall ::= localValue 2
invalidOrUnregisteredCUGIndex InvalidOrUnregisteredCUGIndex ::= localValue 16
requestedBasicServiceViolatesCUGConstraints
RequestedBasicServiceViolatesCUGConstraints ::= localValue 17
outgoingCallsBarredWithinCUG OutgoingCallsBarredWithinCUG ::= localValue 18
incomingCallsBarredWithinCUG IncomingCallsBarredWithinCUG ::= localValue 19
userNotMemberOfCUG UserNotMemberOfCUG ::= localValue 20
inconsistencyInDesignatedFacilityAndSubscriberClass
InconsistencyInDesignatedFacilityAndSubscriberClass ::= localValue 21
END -- Closed-User-Group-Service-Operations
7.2 Coding of the Cause information element
The coding of cause #87 "User not a member of CUG" (for use in the Cause information element in certain CUG service
related circumstances, as described in clauses 9 and 11) is defined in EN 300 485 [15].
ETSI
12 EN 300 138-1 V1.3.4 (1998-06)
8 State definitions
No specifically defined EN 300 403-1 [13] protocol control states shall be required for the CUG supplementary service.
To facilitate understanding of the service the following CUG process states are used in the dynamic description:
- CUG idle;
- outgoing CUG;
- incoming CUG.
These states are specified for the purpose of the protocol definition; these states need not be provided in an
implementation.
9 Signalling procedures at the coincident S and
T reference point
9.1 Activation, deactivation and registration
Not applicable.
9.2 Invocation and operation
NOTE: In a number of cases the procedures in the following subclauses specify that return error information shall
be conveyed from the destination to the originating side. However, the current ISUP implementation (see
ETS 300 356-9 (1995)) does not fully support the conveyance of the return error information to the
originating network as cause values are the only means for conveyance of information. The mapping from
return error information at the destination and vice versa at the origination is specified in annex C.
The CUG supplementary service shall be invoked by:
- a call originating from a CUG supplementary service user. The user may explicitly request the CUG supplementary
service, but in the absence of an explicit request the CUG supplementary service default procedures shall be
automatically applied;
- a call terminating at a CUG supplementary service user.
9.2.1 Call originating from a user with the CUG supplementary service
(explicit request)
9.2.1.1 Normal operation
To request explicitly the CUG supplementary service the calling user shall include in the outgoing SETUP message a
Facility information element containing a cUGCall invoke component. If no Calling party number information element is
included by the calling user in the SETUP message, the default number stored in the originating network shall be used for
the assignment of the CUG.
The network shall perform internal checks appropriate to the originating network based on the contents of the cUGCall
invoke component and the CUG attributes of the calling user. The outcomes of these checks are defined in table 4.
NOTE: The network may respond to the SETUP message with a SETUP ACKNOWLEDGE or CALL
PROCEEDING message or the call may be cleared for some reason unrelated to the CUG supplementary
service before the checks are completed.
ETSI
13 EN 300 138-1 V1.3.4 (1998-06)
If the result of the checks relevant to the originating network side allows the call to proceed then the destination network
shall perform further internal checks based on the CUG attributes (if any) of the called user. The outcomes of these checks
are defined in table 5.
If the call is successfully offered to the called user, then basic call control procedures shall apply at the calling user's
interface.
9.2.1.2 Exceptional procedures
If, as a result of the checks relevant to either the originating or destination network, the network cannot allow the call to
proceed for a CUG supplementary service related reason, then the network shall fail the call attempt and include in the
first clearing message returned to the calling user (before the alerting phase) a Facility information element containing a
cUGCall return error component with the appropriate indication as defined in tables 4 and 5.
The cause in the clearing message conveying the cUGCall return error component should be #29 "Facility rejected".
If the call attempt fails for a reason unrelated to the CUG supplementary service, then a Facility information element
containing a cUGCall return error component indicating "basicServiceNotProvided" should be included in the first
clearing message returned to the calling user (before the alerting phase). The cause cited shall be determined by the event
causing the failure. If there is no cUGCall return error component present in the first clearing message, then the user shall
abandon the CUG call operation and continue normal clearing.
The possibility of "simultaneous" failure for a CUG supplementary service related reason and a reason unrelated to the
CUG supplementary service is not precluded. In this case, if the cUGCall return error component can be sent, it shall
contain an indication as defined by tables 4 and 5, but the cause shall be determined by the event not related to the CUG
supplementary service which caused the call failure.
9.2.2 Call originating from a user with the CUG supplementary service
(default request)
9.2.2.1 Normal operation
If the calling user does not include in the outgoing SETUP message a Facility information element containing a cUGCall
invoke component, the network shall perform internal checks appropriate to the originating network based on the CUG
attributes of the calling user. The outcomes of these checks are defined in table 4. If no Calling party number information
element is included by the calling user in the SETUP message, the default number stored in the originating network shall
be used for the assignment of the CUG.
NOTE: The network may respond to the SETUP message with a SETUP ACKNOWLEDGE or CALL
PROCEEDING message or the call may be cleared for some reason unrelated to the CUG supplementary
service before the checks are completed.
If the result of the checks relevant to the originating network allows the call to proceed then the destination network shall
perform further internal checks based on the CUG attributes (if any) of the called user. The outcomes of these checks are
defined in table 5.
If the call is successfully offered to the called user then basic call control procedures shall apply at the calling user's
interface.
9.2.2.2 Exceptional procedures
If, as a result of the checks relevant to either the originating or destination network, the network cannot allow the call to
proceed for a CUG supplementary service related reason, then the network shall initiate call clearing using one of the
following causes:
- #87 "User not a member of CUG" if the corresponding cUGCall return error component value would have been
"userNotMemberOfCUG" using the explicit request procedures;
- #29 "Facility rejected" in the case of all other CUG supplementary service related reasons.
When a call fails for a reason unrelated to the CUG supplementary service then no CUG supplementary service related
procedures shall apply.
ETSI
14 EN 300 138-1 V1.3.4 (1998-06)
9.2.3 Call originating from a user without the CUG supplementary service
9.2.3.1 Normal operation
A user without the CUG supplementary service can make a call to a user with the CUG supplementary service. If such a
calling user does not include in the outgoing SETUP message a Facility information element containing a cUGCall invoke
component, then table 4 shall apply.
The destination network shall then perform further internal checks based on the CUG attributes (if any) of the called user.
The outcomes of these checks are defined in table 5.
9.2.3.2 Exceptional procedures
If the calling user includes in the outgoing SETUP message a Facility information element containing a cUGCall invoke
component and if the network can recognize this cUGCall invoke component, then the network shall fail the call and
initiate clearing with cause #50 "Requested facility not subscribed". The network shall include in the first clearing
message returned to the calling user a Facility information element containing a cUGCall return error component with the
appropriate indication as defined in table 4, i.e. "notSubscribed".
If the calling user includes in the outgoing SETUP message a Facility information element containing a cUGCall invoke
component but the network cannot recognize this supplementary service request, then the procedures defined in subclause
8.4 of EN 300 196-1 [12] shall apply.
If the calling user does not include in the outgoing SETUP message a Facility information element containing a cUGCall
invoke component and the call fails as a result of the checks relevant to the destination network, then the network shall fail
the call attempt and initiate clearing with cause #87 "User not a member of CUG". No other CUG supplementary service
related indication shall be conveyed to the calling user.
If the call attempt fails for a reason unrelated to the CUG supplementary service, then no CUG supplementary service
related procedures shall apply.
9.2.4 Call terminating at a user with the CUG supplementary service
9.2.4.1 Normal operation
If the internal checks defined in table 5 result in a requirement for a CUG call to the called user, then the incoming SETUP
message shall include a Facility information element containing a cUGCall invoke component to convey the necessary
CUG call information (as defined in table 5).
The network shall then expect either:
a) an ALERTING or CONNECT message according to basic call control received from a connection endpoint
identifier if the call is successfully offered in the user's domain represented by that connection endpoint identifier;
or
b) a cUGCall return error component in a Facility information element in the first clearing message received from a
connection endpoint identifier (before the alerting phase) if the call is failed by the terminal equipment represented
by that connection endpoint identifier. The network shall continue clearing that connection endpoint identifier.
If the network knows that a point-to-point configuration exists then the error value shall be relayed by the network
to the originating network and an appropriate indication (depending on the calling user's CUG supplementary
service invocation being explicit or default) shall be delivered in the first clearing message to the calling user.
In case of a SETUP message sent via the broadcast datalink, the network may, as a network option, retain the return
error component along with the Q.931 cause retained according to subclause 5.2.5.3 of EN 300 403-1 [13]. If there
are multiple clearing messages containing return error components, the indication in the return error component
contained in the first received clearing message with the highest priority cause will be sent back to the calling user.
If none of the clearing messages with the highest priority cause contains return error components and other clearing
messages with lower priority causes do contain return error components, no indication in these return error
components shall be sent back to the calling user.
ETSI
15 EN 300 138-1 V1.3.4 (1998-06)
In addition to the basic call procedures defined in EN 300 403-1 [13], when a user receives a SETUP message with a
Facility information element containing a cUGCall invoke component and the user can recognize CUG call invocation
procedures, the user may:
1) initiate appropriate user domain closed user group procedures and, if the call fails for CUG supplementary service
reasons, may include in the first clearing message returned to the network (before the alerting phase) a Facility
information element containing a cUGCall return error component; or
2) include in the first clearing message returned to the network (before the alerting phase) a Facility information
element containing a cUGCall return error component with value
"inconsistencyInDesignatedFacilityAndSubscriberClass" if the call fails for a reason unrelated to the CUG
supplementary service.
9.2.4.2 Exceptional procedures
If the cUGCall return error component is absent in the first clearing message received from a connection endpoint
identifier the destination network shall continue clearing that connection endpoint identifier for reasons unrelated to the
CUG supplementary service. In addition, if the destination network knows that a point-to-point configuration exists it shall
abandon the CUG call operation and initiate normal call clearing towards the calling user including, if appropriate, a
cUGCall return error component indicating "inconsistencyInDesignatedFacilityAndSubscriberClass".
If no cUGCall return error component is received by the destination network during an unsuccessful call offering process,
then the destination network shall abandon the CUG call operation and initiate call clearing towards the calling user with
the appropriate cause derived from basic call control (e.g. cause #18 "No user responding", or the highest priority cause
saved) including, if appropriate, a cUGCall return error component indicating
"inconsistencyInDesignatedFacilityAndSubscriberClass".
When a user receives a SETUP message with a Facility information element containing a cUGCall invoke component and
the user cannot recognize this supplementary service request, then the procedures defined in subclause 8.4 of
EN 300 196-1 [12] shall apply.
ETSI
16 EN 300 138-1 V1.3.4 (1998-06)
9.2.5 CUG checks at the originating and destination network
Table 4 shall be used to determine the type of call request sent to the destination network or rejection indication returned
to the calling user.
Table 4: CUG checks at the originating network
CUG information received from calling user in SETUP
CUG attributes of CUG call invoke received no
calling user for OA not req. OA req. OA not req. OA req. CUG call
requested basic service CUG index CUG index no CUG index no CUG index invoke
received
CUG call CUG call
no preferential not OCB IC = spec. CUG IC = spec. CUG rejected rejected rejected
CUG (note 1) (note 1) RE value = e RE value = e no RE
OA not allowed rejected rejected (note 4) (note 4) (note 4)
OCB RE value = d RE value = d
CUG call CUG call
no preferential not OCB IC = spec. CUG IC = spec. CUG
CUG (note 1) (note 1) normal call normal call normal call
OA allowed rejected rejected (note 4) (note 4) (note 4)
OCB RE value = d RE value = d
CUG call CUG call CUG call CUG call
preferential not OCB IC = spec. CUG IC = spec. CUG IC = pref. CUG IC = pref. CUG
CUG (note 2) (note 2) rejected
nominated
OA not allowed rejected (note 3) rejected (note 3) rejected (note 5) RE value = a rejected
OCB RE value = d RE value = d RE value = d no RE
(note 5)
CUG call CUG call CUG call CUG call
preferential not OCB IC = spec. CUG IC = spec. CUG IC = pref. CUG IC = pref. CUG
CUG (note 2) (note 2) normal call
nominated
OA allowed rejected (note 3) rejected (note 3) rejected (note 5) rejected
OCB RE value = d RE value = d RE value = d no RE
(note 5)
not a CUG user rejected rejected rejected rejected normal call
RE value = a RE value = a RE value = a RE value = a (note 6)
Key:
IC: CUG interlock code
RE: cUGCall return error component
RE value a: "notSubscribed"
RE value b: "invalidOrUnregisteredCUGIndex"
RE value c: "requestedBasicServiceViolatesCUGConstraints"
RE value d: "outgoingCallsBarredWithinCUG"
RE value e: "inconsistencyInDesignatedFacilityAndSubscriberClass"
NOTE 1: Assumes match between CUG index and IC exists for the requested basic service. If no match exists then:
- if the CUG index exists but is not appropriate to the requested basic service the call shall be rejected
with RE value = c. This includes the case when the requested basic service is not included in any
CUG;
- if the CUG index does not exist the call shall be rejected with RE value = b.
NOTE 2: Assumes match between CUG index and IC exists for the requested basic service. If no match exists then:
- if the CUG index exists but is not appropriate to the requested basic service the call shall be rejected
with RE value = c;
- if the CUG index does not exist the call shall be rejected with RE value = b.
NOTE 3: If the CUG index identifies the preferential CUG then this combination of CUG attribute values is not
recommended.
NOTE 4: This includes the case when the requested basic service is not included in any CUG.
NOTE 5: This combination of CUG attribute values is not recommended.
NOTE 6: This represents the normal case of a user without the CUG supplementary service making a normal call.
NOTE 7: The type of call request derived from this table shall determine the linkage to table 5.
ETSI
17 EN 300 138-1 V1.3.4 (1998-06)
Table 5 shall be used to determine the type of call request sent to the destination user or the type of rejection indication
returned to the calling user.
Table 5: CUG checks at the destination network
Type of CUG CUG CUG attributes of called user for requested basic service
indication match IA not allowed IA allowed not a CUG user
from the network check not ICB ICB not ICB ICB
M CUG call rejected CUG call rejected
CUG call with RE value = e RE value = e rejected
no OA indication NM rejected rejected RE value = f
RE value = f (note 1) RE value = f (note 1)
normal call - rejected normal call normal call
RE value = f (note 2) (note 2) (note 3)
Key:
M: match between IC and CUG index exists for the requested basic service
NM: no match between IC and CUG index exists for the requested basic service
CUG call: cUGCall invoke component in SETUP message identifies CUG index but does not request outgoing
access
normal call: no cUGCall invoke component in SETUP message
IC: CUG interlock code
RE: cUGCall return error component ret
...