scope:

This standard specifies the generic layer three protocol for the control of circuit-switched on demand connections serving ISDN customers via the user-network interface for a variety of applications. These applications are, e.g., the connection of terminals or private ISDNs to the public network applying the point-to-point or the point-to-multipoint mode of operation.

The purpose of this standard is to present the generic layer three signalling requirements for the user-network interfaces.

This standard specifies the stage three of the pan-European Integrated Services Digital Network (ISDN) as provided by European telecommunication operators for the basic call control at the T reference point or coincident S and T reference points (as defined in CCITT Recommendation I.411) by means of the Digital Subscriber Signalling one (DSS1).

This standard specifies the protocol requirements where the service is provided to the user within an ISDN; it does not specify the additional protocol requirements where the service is provided to the user via a telecommunication network that is not an ISDN.

The basic call control according to this standard is applicable to the telecommunication services as described in the appropriate stage one standards

Further standards specify the method of testing and detailed application specific requirements to determine conformance based on this standard.