CONTENTS

        3.1     Scope
        3.2     References
        3.3     Definitions
        3.4     Abbreviations
        3.5     Description
        3.6     Operational requirements
                  3.6.1     Provision/withdrawal
                  3.6.2     Requirements on the originating network side
                  3.6.3     Requirements on the destination network side
        3.7     Coding requirements
        3.8     State definitions
                  3.8.1     User states
                  3.8.2     Network states
        3.9     Signalling procedures at the coincident S and T reference point
                  3.9.1     Procedures at the served user's interface
                  3.9.2     Procedures at the remote user's network interface
       3.10     Procedures for interworking with private ISDNs
                 3.10.1     Procedures for the originating T reference point
                 3.10.2     Procedures for the destination T reference point
       3.11     Interactions with other networks
                 3.11.1     Interactions with non-ISDNs
       3.12     Interactions with other supplementary services
                 3.12.1     Call Waiting (CW)
                 3.12.2     Explicit Call Transfer (ECT)
                 3.12.3     Connected Line Identification Presentation (COLP)
                 3.12.4     Connected Line Identification Restriction (COLR)
                 3.12.5     Calling Line Identification Presentation (CLIP)
                 3.12.6     Calling Line Identification Restriction (CLIR)
                 3.12.7     Closed User Group (CUG)
                 3.12.8     Conference calling (CONF)
                 3.12.9     Direct-Dialling-In (DDI)
                3.12.10     Call diversion (call forwarding) services
                3.12.11     Line Hunting (LH)
                3.12.12     Three-Party service (3PTY)
                3.12.13     User-to-User Signalling (UUS)
                3.12.14     Multiple Subscriber Number (MSN)
                3.12.15     Call Hold (HOLD)
                3.12.16     Advice of Charge (AOC)
                3.12.17     Sub-addressing (SUB)
                3.12.18     Terminal Portability (TP)
                3.12.19     Completion of Calls to Busy Subscribers (CCBS)
                3.12.20     Malicious Call Identification (MCID)
                3.12.21     Reverse charging (REV)
                3.12.22     Multi-level Precedence and Preemption (MLPP)
                3.12.23     Support of Private Numbering Plan (SPNP)
                3.12.24     International Telecommunication Charge Card (ITCC)
                3.12.25     Global Virtual Network Service (GVNS)
       3.13     Parameter values (Timers)
       3.14     Dynamic description (SDLs)
Appendix I – Signalling flows