[SIPForum-discussion] Codec selection with SIP

[Eric Burger]

And then... The real world intervenes.

Many operators prefer compressed codecs.  This can happen, for  
example, in situations where bandwidth is at a premium.  Such  
situations include 2.5G wireless, congested/distant WiFi, low-speed  
DSL, etc.  In this case, carrier equipment often has UAS preferences  
such that even if the UAC prefers G.711, and the UAS supports G.711  
(because RFC 3261 demands it), if the UAC supports G.729, the UAS will  
pick G.729.

On May 30, 2008, at 2:35 PM, Raj Jain wrote:

> You've not shown an SDP offer/answer exchange. But, assuming that A is
> the offerer and presents g711, g729 (in that order) and that B is the
> answerer (that would prefer to have the call setup on g729), then
> it'll put g729 *only* in its answer. That way, the agreed upon codec
> for the session will be g729.
>
> --
> Raj Jain
>
> On Fri, May 30, 2008 at 9:00 AM, José Antonio García Flores
> <joseantonio.garcia at corp.ya.com> wrote:
>> Hi,
>> We want to know how codec is selected in SIP calls, i mean , if A  
>> party has
>> priority over B party.
>> For example:
>> A party:
>>  codec 1 = g711
>>  codec 2 = g729
>> B party:
>>  codec 1 = g729
>>  codec 2= g711
>>
>> At the end, which codec is selected? -> g711?
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