scope:

The present document specifies the extensions of the protocol for basic call control for the pan-European Integrated Services Digital Network (ISDN). These extensions are applicable at the "b" service entry point (as defined in clause 5 of the present document). It is part of the Digital Subscriber Signalling System No. One (DSS1) protocol. The present document contains only additional requirements to those in the main body of ETS 300 403-1 [2]. The present document is applicable only to point-to-point access configurations. The present document specifies additional protocol elements and call control procedures for the handling of calls between users in a Corporate telecommunication Network (CN) at the "b" service entry point. The functionality provided by the public network may be: - the emulation of an Originating Private Integrates services Network Exchange (PINX); - the emulation of a Terminating PINX; - the emulation of a Transit PINX; - the emulation of a Relay Node; - the emulation of an Incoming Gateway PINX; - the emulation of an Outgoing Gateway PINX; - the emulation of a combination of two or more of the above. The support of these capabilities is a network option. The present document does not cover the requirements for support of the "a" service entry point. The specification included in the present document does not imply any specific implementation technology or platform.