Hi, Comments inline ([CHH])
>>[CHH] My understanding is that only the first reliable >>provisoinal response may contain an offer, and only in the >>case that the initial INVITE didn't contain one (in which the >>answer is sent in the first PRACK). >> >>I think that there can only be one offer/answer exchange >>per transaction, so once a SDP (offer or answer) has been >>sent in a provisional response no more can be sent for that >>transaction (INVITE). Or? >> >>IF we were allowed to send more offers in provisional >>responses, how would we handle race conditions if the UAC at >>the same time sends a new offer (we can't send 491 to a >>provisional response)? >> >Well, RFC 3312 certainly calls for multiple offer/answer cycles per >INVITE. (It isn't really one transaction, since it requires PRACK and >the prack is a separate transaction.) [CHH] Yes, but every 18x provisional response is part of the INVITE transaction, and within that single transaction I don't think you can send multiple offers and/or answers. >It is my understanding that once you take account of 3361, 3362, 3364 >and 3311, offer/answer has been decoupled from specific >messages. Within an invite dialog you may have a sequence of offer/answer >exchanges. The main limitations are that each offer must be answered and >that you can't send another offer until the prior one has been answered. [CHH] I agree on that, but I still think you can't send multiple offers and/or answers within a single transaction. Regards, Christer Holmberg Ericsson Finland _______________________________________________ Sip-implementors mailing list [EMAIL PROTECTED] http://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
