scope:

The present document specifies the generic functional protocol for the pan-European Integrated Services Digital Network (ISDN) applicable at the "b" service entry point (as defined in EN 301 060-1 [3]). It is part of the Digital Subscriber Signalling System No. one (DSS1) protocol. The generic functional protocol is based on the Facility information element and the FACILITY message, as well as on other specific functional messages. The protocol is symmetrical, and it is applicable to both basic and primary rate interfaces. The generic functional protocol defined in the present document provides the means to exchange signalling information for the control of supplementary services over a Virtual Private Network (VPN). It does not by itself control any supplementary service but rather provides generic services to specific supplementary service control entities. The application of the present document to individual supplementary services is outside the scope of the present document and is defined in those standards which specify the individual supplementary services. Further part(s) of the present document specify the method of testing required to identify conformance to the present document.