scope:

The present document specifies the stage 3 description of the Supplementary Services CFU Call Forwarding Unconditional, CFB Call Forwarding on Busy, CFNRy Call Forwarding on No Reply and CFNRc Call Forwarding on Not Reachable for the Terrestrial Trunked Radio (TETRA).

SS-CFU, SS-CFB, SS-CFNRy and SS-CFNRc are supplementary services which allow a served user to have a TETRA network send all or specific incoming calls addressed to the served user's TETRA number to another number.

Man-Machine Interface and charging principles are outside the scope of the present document.

The present document is applicable to Voice plus Data individual call or group call; some parts of the present document are applicable to SDS (Short Data Service); more specifically to the following entities:

- the MS of either the calling user or the called user during an individual call or a group call;

- the originating Switching and Management Infrastructure (SwMI) in an individual call or a group call;

- the group controlling SwMI for a group call;

- the terminating SwMI in an individual call;

- the interworking SwMI for an individual call.

The present document is based on the latest version of ECMA-174 [i.1]. Contrary to ECMA-174 [i.1], the present document does not define Call Deflection supplementary service and the present document distinguishes between the case of No Reply and the case of Not Reachable. Moreover, the present document defines the protocol in cases of group calls and of mobility not covered by ECMA-174 [i.1].

The present document also specifies additional signalling protocol requirements for the support of interactions at the ISI reference point, other supplementary services and ANFs. The present document is applicable to SwMIs that can interconnect to form a TETRA network.