CONTENTS

 3     Completion of Calls to Busy Subscriber (CCBS)
        3.1     Introduction
                  3.1.1     Scope
                  3.1.2     References
                  3.1.3     Terms and definitions
                  3.1.4     Abbreviations
        3.2     Description
                  3.2.1     General description
                  3.2.2     Specific terminology
                  3.2.3     Qualification on the applicability to telecommunication services
        3.3     Operational requirements
                  3.3.1     Provision/withdrawal
                  3.3.2     Requirements on the originating network
                  3.3.3     Requirements on the terminating network
                  3.3.4     Requirements on the transit network
        3.4     Coding requirements
                  3.4.1     Introduction
                  3.4.2     Coding requirements
                  3.4.3     ASN.1 module
        3.5     Signalling requirements
                  3.5.1     Activation/deactivation/registration
                  3.5.2     Erasure
                  3.5.3     Invocation and operation
                  3.5.4     Use of TC and SCCP
                  3.5.5     Dialogue
        3.6     Interaction with other supplementary services
                  3.6.1     Call Waiting (CW)
                  3.6.2     Call transfer services
                  3.6.3     Connected Line Identification Presentation (COLP)
                  3.6.4     Connected Line Identification Restriction (COLR)
                  3.6.5     Calling Line Identification Presentation (CLIP)
                  3.6.6     Calling Line Identification Restriction (CLIR)
                  3.6.7     Closed User Group (CUG)
                  3.6.8     Conference Calling (CONF)
                  3.6.9     Direct-Dialling-In (DDI)
                 3.6.10     Call diversion services
                 3.6.11     Line Hunting
                 3.6.12     Three-Party Service (3PTY)
                 3.6.13     User-to-User Signalling (UUS)
                 3.6.14     Multiple Subscriber Number (MSN)
                 3.6.15     Call Hold (HOLD)
                 3.6.16     Advice of Charge (AOC)
                 3.6.17     Sub-addressing (SUB)
                 3.6.18     Terminal Portability (TP)
                 3.6.19     Completion of Calls to Busy Subscriber (CCBS)
                 3.6.20     Malicious Call Identification (MCID)
                 3.6.21     Reverse Charging (REV)
                 3.6.22     Multi-level precedence and preemption (MLPP)
                 3.6.23     Private Numbering Plan (PNP)
                 3.6.24     International Telecommunication Charge Card (ITCC)
                 3.6.25     Global Virtual Network Service (GVNS)
        3.7     Interaction with other networks
                  3.7.1     Interworking with an ISUP network without an ISUP that fully supports the CCBS capability
                  3.7.2     Interworking with a network without CCBS-ASE capability
                  3.7.3     Interworking with a network without SCCP/TC capability
                  3.7.4     Interworking with an intermediate network without 1993 version of SCCP capability
                  3.7.5     Interworking with PSTN with analogue subscribers using the CCBS service            26
                  3.7.6     Interworking with PSTN user
                  3.7.7     Procedures for interworking with private ISDNs
        3.8     Signalling flows
                  3.8.1     Normal call – B busy indication sent to the calling user
                  3.8.2     Normal call – Successful CCBS request followed by a successful CCBS call set-up
                  3.8.3     Unsuccessful CCBS request, terminal activated
                  3.8.4     Unsuccessful CCBS request, network destination
                  3.8.5     Successful CCBS request followed by an unsuccessful CCBS call set-up
                  3.8.6     B idle at CCBS request from A
                  3.8.7     A busy when B becomes free
        3.9     Parameter values
                  3.9.1     Timers in the originating local exchange
                  3.9.2     Timers in the destination local exchange
                  3.9.3     Interworking timers
       3.10     Dynamic description