The present document specifies the stage three Protocol Description of the Closed User Group (CUG) service, based on stage one and two of the ISDN Communication diversion supplementary services. It provides the protocol details in the IP Multimedia (IM) Core Network (CN) subsystem based on the Session Initiation Protocol (SIP) and the Session Description Protocol (SDP).
The present document is applicable to User Equipment (UE) and Application Servers (AS) which are intended to support the CUG supplementary service.
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.
For the purposes of the present document, the terms and definitions given in TS 22.173 and the following apply:
basic service:
bearer or teleservice. Within the scope of SIP based networks the identification of a bearer or teleservice can be derived from the SDP used
Closed User Group (CUG) communication:
closed user group communication is a communication which is restricted to a pre-defined group of users
Closed User Group (CUG) member:
user who has subscribed to the CUG service and is one of the users in the group formed by a particular closed user group
CUG index:
parameter used by the originating user to select a particular CUG when originating a communication
CUG interlock code:
means of identifying CUG membership within the network
CUG manager:
authority representing the interests of all the members of a CUG
incoming access:
arrangement which allows a member of a closed user group to receive communications from outside the closed user group
incoming communications barred within a closed user group:
access restriction that prevents a closed user group member from receiving communications from other members of that group
outgoing access:
arrangement which allows a member of a closed user group to place communications outside the closed user group
outgoing communications barred within a closed user group:
access restriction that prevents a closed user group member from placing communications to other members of that group
preferential 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 communication request