scope:

This second part of ETS 300 138 is applicable to the stage three of the Closed User Group (CUG) 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 CCITT Recommendation I.411 [10]) by means of the Digital Subscriber Signalling System No. one (DSS1). Stage three identifies the protocol procedures and switching functions needed to support a telecommunications service (see CCITT Recommendation I.130 [9]).

This ETS provides the Protocol Implementation Conformance Statement (PICS) proforma for the ISDN DSS1 CUG supplementary service protocol as specified in ETS 300 136 [1] (stage one), ETS 300 137 [2] (stage two) and ETS 300 138-1 [3] (stage three) in compliance with the relevant requirements and in accordance with the relevant guidance given in ISO/IEC 9646-7 [8].