This International Standard specifies the following Identification supplementary services: Calling Line Identification Presentation (SS-CLIP), Connected Line Identification Presentation (SS-COLP) and Calling/Connected Line Identification Restriction (SS-CLIR), which are applicable to various basic services supported by Private Integrated Services Networks (PISN). Basic services are specified in ISO/IEC 11574. Calling Line Identification Presentation (SS-CLIP) is a supplementary service which is offered to the called user and which provides the calling user's PISN number, and possibly a subaddress, to the called user. Connected Line Identification Presentation (SS-COLP) is a supplementary service which is offered to the calling user and which provides the called (connected) user's PISN number, and possibly a subaddress, to the calling user. Calling/connected Line Identification Restriction (SS-CLIR) is a supplementary service offered to a user to restrict presentation of that user's PISN number to another user. Supplementary service specifications are produced in three stages, according to the method described in CCITT Recommendation 1.130. This International Standard contains the stage 1 and stage 2 specifications of SS-CLIP, SS-COLP and SS-CLIR. The stage 1 specifications (clauses 6, 7 and 8) specify the supplementary services as seen by users of PISNs. The stage 2 specifications (clauses 9, 10 and 11) identify the functional entities involved in the supplementary services and the information flows between them.