A phone-sync (also known as a tape-sync, a simul-rec, or a double-ender) was a technique used to conduct televised interviews over long distances in the 1980s before satellite television became commonplace, in order to provide video to what would otherwise be an audio-only interview.
[2] This interviewee, often in a studio in front of a background representing the city in which he or she is located, is videotaped as he or she participates in the interview.
[3] Cuts between shots of the interviewer and interviewee are made accordingly, and the higher-quality sound of the videotapes are used instead of the telephone audio.
For effect, the interviewer may be taped looking into a bluescreen or greenscreen, into which the video of the interviewee would at this point be resized if necessary and inserted using chroma key.
The double-ender technique has become much less commonplace with the proliferation of live satellite television feeds and video over Internet (Skype, etc.