ISO/IEC 21889:2001

Information technology — Telecommunications and information exchange between systems — Private Integrated Services Network — Inter-exchange signalling protocol — Call Identification and Call Linkage Additional Network Feature

Scope

This International Standard specifies the signalling protocol for the support of the Call Identification and Call Linkage
Additional Network Feature (ANF-CIDL) at the Q reference point between Private Integrated Network Services Exchanges
(PINXs) connected together within a Private Integrated Services Network (PISN).
ANF-CIDL is an additional network feature which allows the assignment of a Global Call Identification (GID) to identify a
call end-to-end over the call route (i.e. between the two end PINXs). As an option, a Thread Identification (TID) may be
assigned to different calls which are logically linked together due to the operation of other supplementary services and/or
ANFs. Additionally a Leg Identification (LID) may be assigned, to identify the different legs of a call.
NOTE 1 - This ANF has been developed to support the use of CSTA (ISO/IEC 18051) in a networked environment, i.e. in a PISN. Use of
this ANF for other applications is not precluded.
The Q reference point is defined in ISO/IEC 11579-1.
Supplementary Service specifications are produced in three stages and according to the method specified in ETS 300 387. This
International Standard contains the stage 3 specification for the Q reference point and satisfies the requirements identified by
the stage 1 and stage 2 specifications in ISO/IEC 21888.
The signalling protocol for ANF-CIDL operates on top of the signalling protocol for basic circuit switched call control, as
specified in ISO/IEC 11572, and uses certain aspects of the generic procedures for the control of supplementary services
specified in ISO/IEC 11582.
This International Standard also specifies additional signalling protocol requirements for the support of interactions at the Q
reference point between Call Identification and Call Linkage and other supplementary services and ANFs.
This International Standard is applicable to PINXs which can be interconnected to form a PISN.