call sign 
(also call signal)
noun
A message, code, or tune that is broadcast by radio to identify the broadcaster or transmitter: the brief jingle of the station’s call sign sounded...
- This was the call sign of a Hamburg radio station which broadcast nightly news bulletins in English to the British people.
- The vocal quality of the kookaburra gave it the gig as the original call sign for Radio Australia in the days of short wave broadcasting.
- The FM radio decode feature uses radio data system information to relay the station call sign, song title, or artist, for display on the PC monitor.