[kawl-in]Radio and Television.
  1. a program in which listeners or viewers phone in comments or questions to the host or a person being interviewed.
  2. a live telephone conversation intended for broadcasting between a program's host and a person being interviewed.
  1. of, relating to, or featuring such phone calls or conversations: a call-in program.

Origin of call-in

First recorded in 1960–65; noun use of verb phrase call in Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018