ETS 300 138-1 : 20002

Foreword
1 Scope
2 Normative references
3 Definitions
4 Symbols and abbreviations
5 Description
6 Operational requirements
  6.1 Provision and withdrawal
  6.2 Requirements on the originating network side
  6.3 Requirements on the destination network side
7 Coding requirements
  7.1 ASN.1 description of coding requirements
  7.2 Coding of the Cause information element
8 State definitions
9 Signalling procedures at the coincident S and T
  reference point
  9.1 Activation, deactivation and registration
  9.2 Invocation and operation
10 Procedures for interworking with private ISDNs
11 Interactions with other networks
12 Interactions with other supplementary services
13 Parameter values (timers)
14 Dynamic description (SDL)
  14.1 The closed user group process
  14.2 Relation to basic call control
Annex A (informative): Signalling flows
Annex B (informative): Diagrammatic description of
                       coding requirements
  B.1 CUG call invoke component (typical example)
  B.2 CUG call return error component
History

Specifies the stage three of the pan-European Integrated Services Digital Network (ISDN) as given by European public telecommunications operators for the Closed User Group (CUG) supplementary service at the T reference point or coincident S and T reference point by using the Digital Subscriber Signalling No. one (DSS1). Does not specify the additional protocol requirements where the service is given to the user via a telecommunications network that is not an ISDN. Specifies the protocol requirements at the T reference point where the service is given to the user via a private ISDN.