Answer: busysignal

AnswerCrossword Clue
BUSYSIGNAL

Conversation barrier

BUSYSIGNAL

Phone's "try later"

BUSYSIGNAL

Sound of a communication failure

BUSYSIGNAL
Telephone sound effect.
BUSYSIGNAL
Caller's annoyance
BUSYSIGNALA holdup
BUSYSIGNALPart of phone tag, sometimes
BUSYSIGNALSemaphore on the go?