MusicOnHold( ) Plays Music on Hold indefinitely
MusicOnHold(class)
Plays hold music specified by class, as configured in musiconhold.conf. If omitted, the default music class for the channel will be used. You can use the SetMusicOnHold( ) application to set the default music class for the channel.
Returns -1 on hangup; otherwise, does not return.
; transfer telemarketers to this extension to keep them busy
exten => 123,1,Answer( )
exten => 123,2,Playback(tt-allbusy)
exten => 123,3,MusicOnHold(default)