[asterisk-users] Early audio SIP sequence order question

[Benoit Panizzon]

Hello

We have quite some problems with early audio with our asterisk 1.6.2.15

What we observe is:

Asterisk - Carrier PBX

Asterisk:Invite(+sdp) => Carrier

Carrier starts to send RTP Audio (ignored by Asterisk)

Asterisk <= Carrier:100 Trying
Asterisk <= Carrier:180 Ringing

Asterisk signals Ringing to the caller which in turn generated the ringing 
tone (still ignoring the early audio sent by the carrier).

Asterisk <= Carrier:200 OK(+sdp)
Asterisk:ACK => Carrier

Asterisk starts to send RTP Audio to Carrier

Only now Asterisk starts playing Audio to the caller.

This causes quite troubles, as the price of a value added number is announced 
in early audio in switzerland, giving the caller a chance to hang up before 
the call is established. But the caller connected to asterisk does not hear 
that early audio announcement.

Is this an asterisk bug, or should the carrier have signaled 183 Session 
Progress instead of 180 Ringing?

Kind regards

Benoit Panizzon
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