Radio Equipment and Systems (RES) - Trans-European Trunked Radio (TETRA); Voice plus Data (V+D) - Part 10: Supplementary services stage 1; Part 10-21: Ambience listening; English version ETS 300392-10-21:1996
Terrestrial Trunked Radio (TETRA) - Voice plus Data (V+D) - Part 10: Supplementary services stage 1 - Sub-part 21: Ambience Listening (AL) (Endorsement of the English version EN 300392-10-21 V1.2.1 (2003-09) as German standard)— 2 стр.
