> From: Olle E. Johansson [o...@edvina.net] > > 4 apr 2012 kl. 18:21 skrev Worley, Dale R (Dale): > > - a locally-generated ringback tone for each 180 Ringing that has > > been received (or perhaps one ringback tone for all of the 180's > > together)
Let me amend what I said, that the locally-generated ringback is constructed only if there is no non-silent audio stream associated with the 180's to-tag. > Unfortunately many pstn gateway services deliver ringback in 183, > making it very hard to understand > > 1) That we're in ringing state > 2) That this is a ring tone they want to send and not an operator message > > I have campaigned for forcing ringbacks to 180 with sdp, like you > write above, so that an application can prefer a message delivered by > 183 on top of the ringback. I don't wan't to mix "This phone number > has no subscriber" with a ring tone. I would prefer the mixing, as the call is at that moment doing two distinct things. > SIP implementors of the world: DO NOT SEND RINGBACK WITH A 183 > RESPONSE WITH SDP. I agree with that -- one should ensure that the semantics of the response code are as correct as possible. But I believe that some PSTN circuits don't inform the caller when ringing begins, only when the call is answered. Dale _______________________________________________ Sip-implementors mailing list Sip-implementors@lists.cs.columbia.edu https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
