The following documents contain provisions which, through reference in this text, constitute provisions of the present document.
References are either specific (identified by date of publication, edition number, version number, etc.) or non specific.
For a specific reference, subsequent revisions do not apply.
For a non-specific reference, the latest version applies. In the case of a reference to a 3GPP document (including a GSM document), a non-specific reference implicitly refers to the latest version of that document in the same Release as the present document.
 TR 21.905
" Vocabulary for 3GPP Specifications ".
 TS 22.085
"Closed User Group (CUG) Supplementary Services; Stage 1".
 TS 23.088
"Call Barring (CB) Supplementary Service; Stage 2".
CUG terminology defined in TS 22.085
is applicable to the present document. In addition, the following definitions apply.
CUG Authorisation Functions:
Checks performed by the network to ensure that the integrity of a CUG related call is guarantied. CUG calls are rejected if they do not meet the criteria of these checks.
CUG call, in signalling terms, is a call where CUG information is passed from the originating switching entity to the destination entity.
Code used to select a CUG for an outgoing call, or to indicate an incoming CUG call. Indices are passed between the user and the network and have significance only within the context of a users subscription.
CUG Interlock Code:
Code which uniquely identifies a CUG within a network. The Interlock code is passed from the point of origin to the destination in a CUG call to identify the CUG which has been invoked.
CUG Related Call Barring:
CUG related call barring is call barring applied to a CUG subscriber by the home network when roaming in a non-CUG network. The user is unable to remove CUG related call barring.
Explicit CUG Invocation:
Explicit CUG invocation is where a calling user attempts to invoke a CUG by passing CUG information to the network in a call request.
Implicit CUG Invocation:
Implicit CUG invocation is where the user invokes some default characteristic of a CUG without providing any CUG information in the call request.
Normal call in the context of this CUG TS is a call established from a CUG subscriber where no CUG information is passed from the originating switching entity to the destination entity.
Outgoing Access Indicator:
Indication passed from the point of origin to the destination in a CUG call to indicate that the calling user has subscribed to the Outgoing Access inter-CUG accessibility subscription option.
In addition to those listed below abbreviations used in the present document are listed in TR 21.905
For the purposes of the present document, the following abbreviations apply:
Closed User Group
Interlock code of the preferential CUG
Interlock Code and Outgoing Access indicator.
Incoming Calls Barred within the CUG
Outgoing Calls Barred within the CUG
Suppress Preferential CUG