The present document defines the stage 1 description of the call waiting supplementary service (SS-CW) for the
Terrestrial Trunked Radio (TETRA) as provided by European operators. The stage 1 description is an overall
service description from the user point of view but does not deal with the details of the human interface itself
(see ITU-T Recommendation I.130 [1]).
SS-CW permits a called user to acknowledge an incoming individual call while he is already busy. Subsequently
that user shall have the choice to accept, reject or ignore that incoming call.
The present document specifies the service description of the supplementary service and the procedures to be
expected with successful and unsuccessful outcomes. In addition the present document specifies the interactions
with other TETRA supplementary services and inter-working considerations.
Charging principles are outside the scope of the present document.