scope:

This second part of EN 300 141 is applicable to the stage three of the Call Hold (HOLD) supplementary service for the pan-European Integrated Services Digital Network (ISDN) as provided by European public telecommunications operators at the T reference point or coincident S and T reference point (as defined in ITU-T Recommendation I.411 [11]) by means of the Digital Subscriber Signalling System No. one (DSS1) protocol. Stage three identifies the protocol procedures and switching functions needed to support a telecommunications service (see CCITT Recommendation I.130 [10]). The present document provides the Protocol Implementation Conformance Statement (PICS) proforma for the ISDN DSS1 HOLD supplementary service protocol as specified in EN 300 141-1 [2] in compliance with the relevant requirements and in accordance with the relevant guidance given in ISO/IEC 9646-7 [9]. The supplier of a protocol implementation which is claimed to conform to EN 300 141-1 [2] is required to complete a copy of the PICS proforma provided in annex A of the present document and is required to provide the information necessary to identify both the supplier and the implementation.