[SIPForum-discussion] Offer-Answer SDP

[HM Kias]

The codec preference of origination was g729 and termination also has g729
capabilities. Hence the sdp answer chose g729, so the media session would be
g729.

On Fri, Aug 19, 2011 at 2:46 PM, call foreign <callf4rgn at gmail.com> wrote:

> Hi
>
> I need ideas and explanation on this call scenario;
>
> Origination UA sent multiple codecs;
>
>    v=0
>    o=alice 2890844526 2890844526 IN IP4 host.anywhere.com
>    s=
>    c=IN IP4 host.anywhere.com
>    t=0 0
>    m=audio 62986 RTP/AVP 18 4
>    a=rtpmap:18 G729/8000
>    a=rtpmap:4 G723/8000
>
>
> Termination UA respond with multiple codecs;
>
>    v=0
>    o=bob 2890844730 2890844731 IN IP4 host.example.com
>    s=
>    c=IN IP4 host.example.com
>    t=0 0
>    m=audio 54344 RTP/AVP 18 4
>     a=rtpmap:18 G729/8000
>    a=rtpmap:4 G723/8000
>    a=sendrecv
>
>
> Question:
>
> What would be the actual media on the session considering that the
> OFFER-ANSWER has been completed on the signaling with an INVITE-200OK-ACK
> messages.  Please note the origination has never included attribute
> "a=inactive" on the initial offer.  In addition, termination side responded
> with attribute "a=sendrecv" immediately without an update offer from the
> origination on which codec it choose for the final media stream.
>
> Does this imply that the actual media stream been used on the session is
> G729 if codec preference is considered?
>
> Please share if you have encountered this scenario.
>
> Regards
>
>
>
>
>
>
>
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-- 
HM Kias
91-9443467600
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