A call sign is the letters and numbers which identify a person, vehicle, or organization that is broadcasting on the radio or sending messages by radio.
call sign in British English
or call signal
noun
a group of letters and numbers identifying a radio transmitting station, esp an amateur radio station
Compare call letters
call sign in American English
the letters or, often, numbers and letters assigned to a licensed broadcasting station, amateur radio operator, etc. as identification, as for sending messages
Examples of 'call sign' in a sentence
call sign
The pilot gave his call sign to air-traffic control and alerted the authorities of the hijack.
Forbes, Bryan A SONG AT TWILIGHT (2001)
"I don't remember anybody on our call sign assignment sheet named Sidewalk," he said.