ETSI EN 300 392-12-8

The present document defines the stage 3 description of the Supplementary Service Area Selection (SS-AS) for the Terrestrial Trunked Radio (TETRA).

SS-AS enables the calling user to establish a call in restricting the area where the participating users in a group call or the connected user in an individual call may be located.

Man Machine interface and Charging clauses are outside the scope of the present document.

Supplementary service specifications are produced in three stages according to the method described in ITU-T Recommendation I.130 [i.1]. The stage 1 description specifies the service from the user's point of view (see EN 300 392-10-8 [i.3]). The stage 2 description identifies the functional capabilities and the information flows needed to support the service as specified in its stage 1 description (see EN 300 392-11-8 [i.4]). The present stage 3 description specifies the protocols at the air interface and at the various Inter-System Interfaces (ISI) to support SS-AS.

NOTE: According to ITU-T Recommendation I.130 [i.1], 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.

The present document is applicable to Voice plus Data individual calls or group calls; more specifically to the following entities:

• the MS/LS of the calling user in an individual call or a group call;
• the originating Switching and Management Infrastructure (SwMI) in an individual call or a group call;
• the group home SwMI and the participating SwMIs for a group call;
• the terminating SwMI for an individual call; and
• optionally, the home SwMI of the group or of the MS/LSs involved, for managing the supplementary service.