From: Robert Sparks <[EMAIL PROTECTED]>
On Nov 23, 2007, at 5:12 AM, Christer Holmberg wrote:
> AFTER he has received the answer he may accept only what both
> parties have indicated support for.
I don't think that's right. Can you show me the text that supports
that claim?
Here's section 7 of RFC 3264 (found by Ernst Horvath):
7 Offerer Processing of the Answer
When the offerer receives the answer, it MAY send media on the
accepted stream(s) (assuming it is listed as sendrecv or recvonly in
the answer). It MUST send using a media format listed in the answer,
and it SHOULD use the first media format listed in the answer when it
does send.
The reason this is a SHOULD, and not a MUST (its also a SHOULD,
and not a MUST, for the answerer), is because there will
oftentimes be a need to change codecs on the fly. For example,
during silence periods, an agent might like to switch to a comfort
noise codec. Or, if the user presses a number on the keypad, the
agent might like to send that using RFC 2833 [9]. Congestion
control might necessitate changing to a lower rate codec based on
feedback.
The offerer SHOULD send media according to the value of any ptime and
bandwidth attribute in the answer.
The offerer MAY immediately cease listening for media formats that
were listed in the initial offer, but not present in the answer.
I skimmed draft-ietf-sipping-sip-offeranswer-04 and I see nothing in
it that would alter the interpretation of this section.
Dale
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