Re: [rtcweb] Same answer in a provisional and a final response

[Roman Shpount <[e-mail]>]

On Mon, Nov 14, 2011 at 11:30 PM, Randell Jesup <[e-mail]>wrote:

> On 11/14/2011 9:38 PM, Gonzalo Camarillo wrote:
>
>> Hi,
>>
>> with respect to today's discussion during the face-to-face session about
>> whether a SIP UAS needs to place the same answer in a final response as
>> it placed in a previous provisional response, this is the relevant text
>> in RFC 3261:
>>
>> http://tools.ietf.org/html/**rfc3261#page-80<http://tools.ietf.org/html/rfc3261#page-80>
>>
>>         "If the initial offer is in an INVITE, the answer MUST be in a
>>          reliable non-failure message from UAS back to UAC which is
>>          correlated to that INVITE.  For this specification, that is
>>          only the final 2xx response to that INVITE.  That same exact
>>          answer MAY also be placed in any provisional responses sent
>>          prior to the answer."
>>
>
> Yes, though I'll note that differing 200 OK's from 18x provisionals is in
> my experience far more common than identical 200 OK's.  (As Cullen alluded
> to.)
>
>
The above mentioned quote from RFC 3261 only means that the same SDP must
be present in 200 OK and 18x provisional for the same dialog. If you have
an early dialog and different final dialog (different to tags in 18x and
200), it is legal, and, in fact, expected to have different SDPs.
_____________
Roman Shpount