call sign

noun2

1. •
   A combination of letters and numbers used to identify a radio or television station.
2. •
   Any combination of characters or pronounceable words, which identifies a communication facility, a command, an authority, an activity, or a unit; used primarily for establishing and maintaining communications.

   • Charlie: I'm Charlotte Blackwood. Maverick: I'm Maverick. Charlie: Did your mother not like you? Maverick: No, it's my call sign. — 1986