CSA Group Information Technology - Telecommunications and Information Exchange Between Systems - Private Integrated Services Network - Specification, Functional Model and Information Flows - Recall Supplementary Service (Adopted ISO/IEC 15051:2003, second edition,

Scope This International Standard specifies supplementary service Recall (SS-RE), which is applicable to various basic services supported by Private Integrated Services Networks (PISN). Basic services are specified in ISO/IEC 11574. SS-RE is a supplementary service which provides for the redirection of a call transferred by the served user back to the served user if the call is unanswered. SS-RE is only applicable after transfer by join, not after transfer by rerouting.Service specifications are produced in three stages, according to the method described in ETS 300 387. This International Standard contains the stage 1 and stage 2 specifications of SS-RE. The stage 1 specification (clause 6) specifies the supplementary service as seen by users of PISNs. The stage 2 specification (clause 7) identifies the functional entities involved in the supplementary service and the information flows between them.