scope:

This draft European Telecommunication Standard (ETS) 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 this ETS.

The supplementary service stage 3 description is preceded by the stage 1 and the stage 2 description of the service, according to the method described in CCITT recommendation I.130 [26]. The stage 1 description specifies the service from the user's point to view. The stage 2 description identifies the functional capabilities of each SS and the information flows needed to support the supplementary service as specified in its stage 1 description. The present stage 3 description specifies the protocols at the air interface and at the various Inter-System Interfaces (ISI) to support each Supplementary service.

NOTE:  According to CCITT Recommendation I.130 [26], the stage 3 description of any telecommunication service addresses the network implementation aspects. Consequently it comprises two steps: the specifications of all protocols at the various reference points involved in any of the service procedures (notably the service operation) are the first step of the stage 3 description, and the specifications of the functions of the corresponding network entities are its second step. The latter have not been provided since they can be derived from the specification of the functional entity actions in the stage 2 description.

This ETS is applicable to Voice plus Data individual call or group call; some parts of this ETS are applicable to SDS (short Data Service); this ETS is neither applicable to Packet Mode of Operation nor to DMO; more specifically to the following entities:

- the MS/LS 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 inter-working SwMI for an individual call.

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

This ETS also specifies the signaling protocol for the support of the Forwarding Counter (FC) at the ISI reference point between SwMIs connected together within a TETRA Network.

FC is a feature that limits the number of Call Forwarding that a Call set-up request may encounter e.g., to protect the network against indefinite looping. FC is associated to Call Forwarding by Forward Switching, itself associated to Individual call only. The signaling protocol for FC operated in association with the signaling protocols for basic circuit switched call control (as specified in ETS 300 392-2 [4] or ETS 300 392-3-2 [8] and call independent (connection oriented) signaling connections (as specified in ETS 300 392-9 [6]).

This ETS also specifies additional signaling protocol requirements for the support of interactions at the ISI reference point between FC and other supplementary services and ANFs. This ETS is applicable to SwMIs that can interconnect to form a TETRA Network.