scope:

This first part of EN 300 356 specifies procedures to support basic bearer services and supplementary services defined for the pan-European Integrated Services Digital Network (ISDN) as provided by the European public telecommunications operators by means of the Signalling System No.7 protocol for the ISDN User Part (ISUP). The present document does not specify the additional protocol requirements where the service is provided to the user via a telecommunications network that is not an ISDN. Although the present document applies only to the international interconnection, the specification of functions, formats and codes of messages and signals, and actions performed at originating and destination local exchanges are retained. Formats, codes and procedures marked for national use are included for informative purposes for the international interface specification. If these items so marked are supported within a national network and operator's network, then it is proposed that they shall be supported in this manner. Items in the present document marked "not required" are not required to be supported.