[AVTCORE] Re: BUNDLE question - relationship to PR-Answer?

[Roman Shpount <[e-mail]>]

Paul,

On Wed, Apr 22, 2026 at 11:31 AM Paul Kyzivat <[e-mail]> wrote:

> Roman,
>
> As I recall, the webrtc offer/answer was initially derived from the sip
> offer/answer. I had the impression that one goal was to preserve the
> ability for them to interoperate. But I imagine that might not have
> turned out to be useful in practice. But then you have to ensure your
> specifications cover all the corner cases. In sip that turned out to be
> remarkably complex.
>
>
It is derived from the SIP offer/answer model. The issue is that there are
no dialogs in this API. How dialogs are mapped to the offer/answer model is
up to singaling protocol implementation. So, the question was, what do you
do if you end up with multiple dialogs as a result of the negotiation?
Option one was to switch the existing negotiation session to use the answer
received in the new dialog (hence the PR-Answer and Answer concepts).
Option two is to ignore the received answer and start a re-negotiation in
the new dialog (i.e., create a new PeerConnection and start a new
offer/answer session). This tracks what SIP does with multiple dialogs.
Option one is an optimization that prevents audio disruption in common call
scenarios, such as calls going to voicemail after hearing the custom
ring-back.

Best regards,
_____________
Roman Shpount