About draft-camarillo-sipping-precons-00:
The draft suggests UAS first using the modification in media level when resume from suspending state.
But if Re-INVITE has no Offer, the Offer in 183 from UAS, the the answerer is UAC. And it is UAC needing user's confirmation.
If people restrict that it is UAS first using new modification after suspending state for all the situation, it can solve the deadlock problem.
But it will be violation of RFC3264.
Deadlock problem:
If people restrict that any later modification during suspending state is part of the ini-Offer/Answer in Re-INVITE.
Then, both UAC and UAS can be answerer.
For examle, during suspending state, UAC added vedio stream(UAS is the answerer), then UAS changed the codec(UAC is the answerer).
Then, the UAC wait UAS using new stream, but UAS wait UAC using the new codec. That is deadlock.
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