ITU-T Q.953.4 PDF

This Recommendation specifies the stage three of the Terminal Portability (TP) supplementary service for the Integrated Services Digital Network (ISDN) at the T reference point or coincident S and T reference point (as defined in Recommendation I.411 [1]) by means of the Digital Subscriber Signalling System No. 1 (DSS 1). Stage three identifies the protocol procedures and switching functions needed to support a telecommunications service (see Recommendation I.130 [2]).

In addition, this Recommendation specifies the protocol requirements at the T reference point where the service is provided to the user via a private ISDN.

This Recommendation does not specify the additional protocol requirements where the service is provided to the user via a telecommunications network that is not an ISDN.

Terminal Portability is a supplementary service that allows the user during the Active call state of a call:

– to suspend the call and to reactivate it subsequently at the same terminal; or

– to move one terminal from one socket to another within one given basic access; or

– to move one call from one terminal to another terminal within one given basic access.

The portability of a terminal during the Null call state is part of the basic access capabilities and does not require any procedure.

The portability of a terminal in the call establishment and in the call clearing phases is not possible.

It is a user's responsibility to resume the call with a terminal which is compatible both with the remote terminal and the type of connection previously established.

The TP supplementary service is applicable to all circuit-switched telecommunication services requiring the attendance of a human being, such as telephony, videotelephony, etc.

The TP supplementary service does not apply to non-interactive services such as facsimile, teletex, mixed-mode, computer communication, etc. However, the network will not take any action to its applicability.

Further part(s) of this Recommendation shall specify the method of testing required to identify conformance to this Recommendation.

This Recommendation is applicable to equipment, supporting the TP supplementary service, to be attached at either side of a T reference point or coincident S and T reference points when used as an access to the public ISDN.