1 Closed User Group (CUG)

04.853GPPClosed User Group (CUG) supplementary servicesStage 3TS

1.1 Normal operation

1.1.1 Mobile originated CUG calls

1.1.1.1 Successful operation

CUG calls may be invoked Implicitly or Explicitly by the calling user.

In the case of Implicit invocation, no CUG information is provided by the user in the call set-up request and a default attribute of CUG is invoked. Normal call establishment procedures are followed over the radio interface and no CUG signalling is required.

In the case of Explicit CUG invocation, CUG information is provided by the user and is included in the SETUP message using the ForwardCUG-Info operation (see figure 1.1). User provided CUG information may consist of any combination of the following parameters:

‑ CUG Index;

‑ Suppress Preferential CUG indicator;

‑ Suppress OA indicator.

NOTE: No more than one of each parameter may be included per call attempt.

MS Network

SETUP

————————————————————————————————————————>

Facility (Invoke = ForwardCUG-Info (CUG-Index, SuppressPrefCUG, SuppressOA))

Figure 1.1: Transfer of CUG information during CUG call set-up

If the network received a non-zero SS Screening indicator from the calling user’s mobile station, the network may optionally indicate to the MS that a CUG has been invoked for a call (see figure 1.2). When a CUG Index is received from the VLR the MSC shall send it immediately to the MS in a FACILITY or CALL PROCEEDING message. If the network did not receive a non-zero SS Screening indicator from the calling user’s mobile station, it shall not send this notification.

MS Network

FACILITY/CALL PROCEEDING

<————————————————————————————————————————

Facility (Invoke = NotifySS (CUG-Index))

Figure 1.2: Indication of CUG invocation to the calling subscriber by the network

1.1.1.2 Unsuccessful operation

When an attempted CUG call is rejected for CUG related reasons, the mobile station is provided with an indication of the reason for failure.

The indication is passed to the calling MS in the first clearing message. The indication may be given in one of two ways:

‑ Diagnostics information in cause value #29 "Facility Rejected";

‑ A standard call control cause value.

Diagnostics are used when the rejection is generated locally (the serving VLR has rejected the call), or if they are provided in a cause value from a remote network node (see figure 1.3). Table 1.1 gives the diagnostics information for each potential local rejection case.

A CUG rejection from a remote network node is generally indicated using a standard (CUG related) call control cause value contained in an ISUP clearing message. These cause values are passed to the mobile station in the appropriate radio interface clearing message (see figure 1.4). Table 1.2 gives the cause values in each potential remote rejection case.

All CUG related call rejection cases are defined in GSM 03.85. Cause values are defined in GSM 04.08 and diagnostics in GSM 04.80.

NOTE: Annex A specifies the mapping of cause values between MAP, ISUP and GSM 04.08 for remotely generated CUG rejections.

MS Network

DISCONNECT/RELEASE/RELEASE COMPLETE

<————————————————————————————————————————

…..Cause #29 (Facility Rejected (diagnostics))…..

Figure 1.3: Indication of local CUG call rejection

MS Network

DISCONNECT/RELEASE/RELEASE COMPLETE

<————————————————————————————————————————

Cause Information Element (Cause Value)

Figure 1.4: Indication of remote CUG call rejection

Table 1.1: Use of diagnostic values for local CUG call failure indications

Reason for rejection
See GSM 03.85

Facility Rejected #29
Diagnostic Field
(Diagnostics)

Outgoing calls barred within the CUG

Outgoing calls barred within the CUG

Inconsistent access info – No CUG Selected

No CUG Selected

Unknown CUG Index

Unknown CUG Index

Inconsistent access info –
Index incompatible with requested basic service

Index incompatible with requested basic service

Table 1.2: Use of cause values for remote CUG call failure indications

Reason for rejection
See GSM 03.85

Cause Information Element
(cause value)

Called party supplementary service interaction violation

Facility Rejected #29
Diagnostic = CUG call failure,
unspecified

Incompatible Destination
(see note)

Facility Rejected #29
Diagnostic = CUG call failure,
unspecified

Incoming calls barred within the CUG

Incoming calls barred within
the CUG #55

Interlock mismatch

User not a member of CUG #87

Requested basic service violates CUG constraints

Facility Rejected #29

NOTE: In cases of interworking failures ETSI ISUP V2 clears the call with cause value #29 "Facility Rejected", Diagnostic = "Interlock Code". This is mapped to Facility Rejected with general diagnostic value "CUG call failure, unspecified" since the interlock code has no meaning for a mobile user.

1.1.2 Mobile terminated calls

If the network received a non-zero SS Screening indicator from the called user’s mobile station, when a CUG call is terminated by a CUG subscriber the Index associated with the invoked CUG may be passed to the mobile station (see figure 1.5). If the network did not receive a non-zero SS Screening indicator from the called user’s mobile station, it shall not send this notification.

MS Network

SETUP

<————————————————————————————————————————

Facility (Invoke = NotifySS (CUG-Index))

Figure 1.5: Presentation of the CUG Index to a CUG subscriber during reception of a CUG call

1.2 Activation, deactivation, interrogation, registration and erasure

Activation, deactivation, interrogation, registration and erasure of the supplementary service closed user group are not applicable.

Annex A (normative):
CUG rejection cause value mapping

Table A.1 indicates how MAP, ISUP and GSM 04.08 cause values are mapped to enable a rejection indication to be passed from the remote rejecting node to the calling user.

Table A.1: Protocol mapping for CUG call rejection cause values

GSM MAP

CUG reject cause value

CCITT ISUP
cause value

GSM 04.08
cause value

calledPartySupplementary-ServiceInteractionViolation

#29 Facility Rejected
Diagnostic = IC
(see note 1)

#29 Facility Rejected
Diagnostic = CUG call failure,
unspecified

incomingCallsBarredWithinCUG

#55 I/C calls barred
within CUG

#55 I/C calls barred
within CUG

subscriberNotMemberOfCUG

#87 User not member
of CUG

#87 User not member
of CUG

requestedBasicService-ViolatesCUGConstraints

#29 Facility Rejected
(see note 2)

#29Facility Rejected
(no diagnostic)

NOTE 1: There is no specific cause value in ISUP for this rejection case. Therefore it is proposed that Cause Value #29 "Facility Rejected" is used with the diagnostic equal to the interlock of the call. This approach has been used in ISUP for interworking problems.

NOTE 2: There is no specific cause value in ISUP for this rejection case. It is therefore proposed to use cause value #29 "Facility Rejected" to indicate a general supplementary service failure.

Annex B (informative):
Change Request History

Status
of
Technical Specification GSM 04.85

Date Version Remarks

No Phase 1 version

June 1992 version 4.0.0 TS approved by SMG#03
Reference to PNP removed
TS frozen for Phase 2 by SMG#05

October 1993 version 4.0.1 TS changed to draft prETS 300 569

October 1994 version 4.0.2 TS changed to final draft prETS 300 569

January 1995 version 4.0.3 TS changed to ETS 300 569 First edition

April 1996 version 4.1.0 CR 04.85-A001 rev 1 (category F) agreed by SMG#18

November 1996 version 4.1.1 TS changed to ETS 300 569 Second edition

December 1996 version 5.0.0 ETS changed to GTS for release ’96

January 1999 version 6.0.0 Release 1997 version

August 1999 version 7.0.0 Release 1998 version

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