The present document defines the stage 1 description of the call hold supplementary service (SS-HOLD) 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-HOLD enables a user to interrupt communication on an existing individual call and then subsequently, if desired, re-establish communication. The present document specifies the service description of the supplementary service and the procedures to be expected with successful and unsuccessful ou