This Recommendation is one of a set of Recommendations that describe the Broadband ISDN User Part. It specifies an overview of the signalling capabilities and functions required to support basic call and bearer services, additional features and supplementary services for B-ISDN applications. The scope of the B-ISDN User Part covers international B-ISDN networks. However, the B-ISDN User Part is suitable for national applications. Most signalling procedures, information elements and message types specified for international use are also required in typical national applications.