Congestion( ) Indicates congestion on the channel
Congestion([timeout])
Requests that the channel indicate congestion and then waits for the user to hang up or for the optional timeout (in seconds) to expire.
This application only signals congestion; it doesn't actually play a congestion tone to the user. You can use Playtones(congestion) to play a congestion tone to the caller.
Always returns -1.
; if the Caller ID is 555-1234, always play congestion
exten => 123,1,GotoIf($[${CALLERIDNUM} = 5551234]?5:2)
exten => 123,2,Playtones(congestion)
exten => 123,3,Congestion( )
exten => 123,4,Hangup( )
exten => 123,5,Dial(Zap/1)