DS EN 300392-10-21:2005
DS EN 300392-10-21:2005 Terrestrial Trunked Radio (Tetra) - Part 10: Supplementary Services Stage 1 - Sub-Part 21: Ambience Listening (Al) Describes the stage 1 specifications of the Ambience Listening (AL) supplementary service for the Trans-European Trunked Radio (TETRA).