[asterisk-users] Providing Ringback

Grey Man greymanvoip at gmail.com
Fri Nov 7 21:44:39 CST 2008

Hi Igor,

We had an interconnect with a carrier that generated early media for
progress indications but the carrier's switch, in this case a Cerpack,
would only start sending the RTP for the early media AFTER it received
an RTP packet from the Asterisk end. Completely stupid behaviour since
early media is generally only one way but that's what it did.

We worked around it by recording 200ms of silence and playing that
back to the carrier's Cerpack with the Background command whenever we
received an incoming call. This got two way RTP set up and allowed the
progress tones to be correctly passed through to the user.

exten => _X.,1,Background(/var/lib/asterisk/custom-sounds/silence_200,n)
exten => _X.,2,Goto(incoming, ${EXTEN}, 1)



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