CONTENTS

 1     Scope
 2     References
 3     Terms and definitions
 4     Abbreviations and acronyms
 5     SS-CI service description
        5.1     Implementation options
        5.2     Provision of capability and protection levels
        5.3     Normal procedures
                  5.3.1     Activation/deactivation/registration/interrogation
                  5.3.2     Invocation and operation
                  5.3.3     Exceptional procedures
        5.4     Interactions with other supplementary services
                  5.4.1     Call Transfer (SS-CT)
                  5.4.2     Call Forwarding Unconditional (SS-CFU)
                  5.4.3     Call Forwarding Busy (SS-CFB)
                  5.4.4     Call Forwarding on No Reply (SS-CFNR)/Call Deflection (SS-CD)
                  5.4.5     Call Hold
                  5.4.6     Call Park/Call Pickup
                  5.4.7     Call Waiting
                  5.4.8     Message Waiting Indication
                  5.4.9     Name Presentation
                 5.4.10     Completion of Calls to Busy Subscriber (SS-CCBS)
                 5.4.11     Completion of Calls on No Reply (SS-CCNR)
                 5.4.12     Call Offer (SS-CO)
                 5.4.13     Common information
                 5.4.14     Call Linkage
 6     Messages and information elements
 7     Signalling procedures
        7.1     Actions at user A's endpoint
                  7.1.1     Procedure for initial invocation of SS-CI
                  7.1.2     Optional procedure for invocation of isolation
                  7.1.3     Optional procedure for invocation of forced release
                  7.1.4     Optional procedure for invocation of wait-on-busy
                  7.1.5     Optional procedure for (re-)invocation of SS-CI on a waiting call
                  7.1.6     Procedure for completion of SS-CI
        7.2     Actions at user B's endpoint
                  7.2.1     Procedure for invocation of SS-CI
                  7.2.2     Optional procedures for invocation of isolation
                  7.2.3     Optional procedures for invocation of forced release
                  7.2.4     Optional procedures for wait-on-busy (WOB)
                  7.2.5     Procedures for completion of SS-CI
        7.3     Actions at user C's endpoint
 8     Interworking and interactions
        8.1     Interworking with SCN
        8.2     Protocol interaction between SS-CI and other supplementary services
                  8.2.1     Call Transfer (SS-CT)
                  8.2.2     Call Forwarding Unconditional (SS-CFU)
                  8.2.3     Call Forwarding Busy (SS-CFB)
                  8.2.4     Call Forwarding on No Reply (SS-CFNR)/Call Deflection (SS-CD)
                  8.2.5     Call Hold
                  8.2.6     Call Park/Call Pickup
                  8.2.7     Call Waiting
                  8.2.8     Message Waiting Indication
                  8.2.9     Name Presentation
                 8.2.10     Completion of Calls to Busy Subscriber (SS-CCBS)/on No Reply (SS-CCNR)
                 8.2.11     Call Offer (SS-CO)
                 8.2.12     Common Information
                 8.2.13     Call Linkage
 9     Gatekeeper/Proxy actions
        9.1     Gatekeeper passes on SS-CI operations to the endpoint
        9.2     Gatekeeper/proxy acts on behalf of an endpoint
                  9.2.1     Gatekeeper/proxy acts on behalf of endpoint A
                  9.2.2     Gatekeeper/proxy acts on behalf of endpoint B
                  9.2.3     Gatekeeper/proxy acts on behalf of endpoint C
10     Dynamic description
       10.1     Operational model
       10.2     Signalling flows
                 10.2.1     Successful SS-CI - direct call signalling
                 10.2.2     Unsuccessful SS-CI
                 10.2.3     Successful SS-CI – GK routed call signalling
       10.3     Communication between an endpoint A signalling entity (EASE) and its Signalling entity user (for information purposes)
                 10.3.1     Table of primitives
                 10.3.2     Primitive definition
                 10.3.3     Parameter definition
       10.4     Communication between an endpoint B signalling entity (EBSE) and its signalling entity user (for information purposes)
                 10.4.1     Table of primitives
                 10.4.2     Primitive definition
                 10.4.3     Parameter definition
       10.5     Communication between an endpoint C signalling entity (ECSE) and its signalling entity user (for information purposes)
                 10.5.1     Table of primitives
                 10.5.2     Primitive definition
                 10.5.3     Parameter definition
       10.6     Call states
                 10.6.1     Call states at endpoint A
                 10.6.2     Call states at endpoint B
                 10.6.3     Call states at endpoint C
       10.7     Timers
                 10.7.1     Timers at endpoint A
                 10.7.2     Timers at endpoint B
11     Operations in support of Call Intrusion supplementary service
12     Specification and description language (SDL) diagrams for SS-CI
       12.1     Behaviour of user A's endpoint
       12.2     Behaviour of user B's endpoint
       12.3     Behaviour of user C's endpoint