Sometimes when I access IRLP nodes, they have a very short melody telling you that you are connected; or when my local repeater's net begins, it does the famous doorbell 8-note sequence. What is the fine line of prohibited and allowed with respect to music?
Is it that overtone usage, like a Sine-wave 6 tone melody, is allowed, but if a piano is used, it would be prohibited?
Or is it the length, like a 2-second little access melody, is allowed, but it can't go on forever?
Or is it what we define as common music, like a 3 minute song, would be prohibited, but random sequences of sine waves for a few seconds would be allowed?
DTMF in a sense could be avant-garde music from John Cage or Karlheinz Stockhausen, who loved the sounds on his shortwave radio and incorporated all of the unique sounds he heard in his music.
So what breaks the barrier for the FCC rules on music or other non-voice audio transmissions?