scope:

The present document defines the stage 3 specifications of the Supplementary Service Call Authorized by Dispatcher (SS-CAD) for the Terrestrial Trunked RAdio (TETRA) as provided by European operators. Stage 3 defines the signalling system protocols needed to implement the service described in stage 1 and stage 2. The stage 1 and stage 2 aspects are detailed in ETS 300392-10-6 [2] and EN 300392-11-6 [3] respectively. Aspects relating to all supplementary services are detailed in EN 300392-9 [6]. Charging principles and the Man-Machine Interface (MMI) are outside the scope of the present document. The SS-CAD ensures that predefined TETRA calls do not proceed without first being authorized by a dispatcher.