Radio broadcasting is a one-way wireless transmission over radio waves intended to reach a wide audience. Stations can be linked in radio networks to broadcast a common radio format, either in broadcast syndication or simulcast or both. Audio broadcasting also can be done via cable radio, local wire television networks, satellite radio, and internet radio via streaming media on the Internet.
The signal types can be either analog audio or digital audio.
A request line or contest line is a telephone line which allows listeners to a radio station (or sometimes a TV station) to call the radio studio or TV studio directly. In radio, this is usually to request a song, win a contest, be a part of a talk show, or to ask a question of the disk jockey, such as what the name and artist of a recent song was. Used occasionally in television, it is typically for telephone voting for an unscientific opinion poll in relation to news events, for a talk show, or sometimes to win a contest.
Although only one telephone number is usually announced, major stations typically have line hunting, with the same number being directed to any available one of several lines within the hunt group. If there are no open lines, the calling party may receive a busy signal as with an ordinary telephone call, or sometimes the special information tones followed by a recorded announcement that "all circuits are busy, please try your call again later". In this case, the line often first gives that caller a ringback tone as if the call were being completed, misleading callers to think they may have actually gotten through the swarm of other calls that sometimes flood these lines.
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