Radio Equipment and Systems (RES); Trans-European Trunked Radio (TETRA); Voice Plus Data (V+D); Part 11: Supplementary Services (SS) Stage 2; Part 11-21: Ambience Listening (AL)
This European Telecommunication Standard (ETS) defines the stage 2 specification of the Supplementary Service Ambience Listening (SS-AL) for the Trans-European Trunked Radio (TETRA) as provided by European operators. Stage 2 identifies the functional entities involved in the supplementary service and the information flows between them. Charging principles and Man-Machine Interface (MMI) are outside the scope of this ETS. The SS-AL enables a served user to place a TETRA Mobile Station (MS) or Line Station (LS) into a special type of voice call teleservice whereby the called MS (or LS) transmits without any action from@ or indication to@ the affected user. The teleservice may include a second listening party.