ZapBarge() — Barges in on (monitors) a Zap channel
Barges in on a specified Zap
channel, or prompts if one is not specified.
The people on the channel won’t be able to hear you and will have no
indication that their call is being monitored.
If channel is not specified, you will
be prompted for the channel number. Enter 4# for Zap/4, for example.
exten => 123,1,ZapBarge(Zap/2)
exten => 123,2,Hangup()