ITU-T Q.956.3 PDF

This Recommendation specifies the stage three of the Reverse Charging (REV) supplementary for 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 telecommunication 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.

The REV supplementary service is a supplementary service allowing a called user to be charged for the actual communication, that is for usage-based calls.

Four cases of reverse charging are distinguished:

– Case A: Reverse charging requested by the calling user at call set-up time;

– Case B: Reverse charging for the rest of the call requested by the calling user or the called user during the active phase of the call;

– Case C: Reverse charging for the entire call requested by the called user during the active phase of the call;

– Case D: Reverse charging unconditional.

NOTE – The calling user should not be provided with a bearer connection until the option of charging, either normal or reversed has been resolved.

The REV supplementary service is applicable to all telecommunication services.

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 REV supplementary service, to be attached at either side of a T reference point or coincident S and T reference point when used as an access to the public ISDN.