The present document specifies the stage three of Support of ATM end system addressing format by Number
identification supplementary services for the pan-European Broadband Integrated Services Digital Network (B-ISDN)
as provided at the TB reference point or coincident SB and TB reference points (as defined in
ITU-T Recommendation I.413 [18]) by means of the Digital Subscriber Signalling System No. two (DSS2) protocol.
Stage three identifies the protocol procedures and switching functions needed to support a telecommunications service
(see CCITT Recommendation I.130 [10]).
In addition, the present document specifies the protocol requirements at the TB reference point where the service is
provided to the user via a private B-ISDN.
NOTE 1: Procedures at the TB reference point, to support the access of a private B-ISDN to the public B-ISDN, are
not explicitly identified in the present document, however, some procedures are applicable only at the TB
reference point.
A basic telecommunications service is a fundamental type of service. It forms the basis on which supplementary
services may be added.
NOTE 2: Specific requirements of individual B-ISDN connection-oriented basic telecommunication services are
not covered by the present document.
Further parts of the present document provide the method of testing and detailed application specific requirements to
determine conformance to the present document.
The present document is applicable to equipment supporting connection-oriented basic B-ISDN telecommunication
services, to be attached at either side of a TB reference point or coincident SB and TB reference points when used as an
access to the public B-ISDN.