SSH ETS 300 392-12-20:1999 ed.1

Terrestrial Trunked Radio (TETRA); Voice plus Data (V+D); Part 12: Supplementary services stage 3; Sub-part 20: Discreet Listening (DL)

Scope

This European Telecommunication Standard (ETS) specifies the stage 3 description of the Supplementary Service Discreet Listening (SS-DL) for the Terrestrial Trunked Radio (TETRA). The DL supplementary service shall enable an authorized user to listen to one or more communications between TETRA subscribers (Mobile Station (MS) or Line Station (LS)) without any indication to any user that the communication is being monitored. As options, the authorized user shall be able to intrude into the existing call and shall be able to forcefully clear the monitored call without call owner consent (in the case of a group call). Man-Machine Interface (MMI) and charging principles are outside the scope of this ETS.