, także:
callsign
,
cal letters
,
call signal
This call sign must stay with the message to the point of delivery.
Let me know your call sign when you check out with operations.
It had stuck all these years, as first call signs usually do.
Each call sign may be used for 15 days from its issue.
I tried the call sign three times with no answer.
That's your call sign, at least the one you're using on this mission.
Immediately he heard a man speaking his call sign on the radio.
Both will have the same call sign as the main signal.
"He used the other call sign and we all bought it!"
Each country has a different set of patterns for its own call signs.