I second Attila. Therefore if you want to use G729 Annex A encoding, do so
using G729 in a-line of sdp, and encode using
G729 annex A in bearer. G729 and "G729 Annex A" are inter-operable and there
should be no difficulties.

However you should specifically mention "annexb=no" as absence of this
parameter implies G729 Annex B
usage as mentioned in RFC4856 section 2.1.9

"        annexb: indicates that Annex B, voice activity detection, is
        used or preferred.  Permissible values are "yes" and "no"
        (without the quotes); "yes" is implied if this parameter is
        omitted.
"


2008/11/3 Attila Sipos <[EMAIL PROTECTED]>

> no, annexb and annexa are different things:
> annexa is a codec efficiency improvement
> annexb is silence suppression
>
> In practice, I have seen usage of "rtpmap:18 G729a/8000"
> but it has no RFC-based meaning.
>
> There is no way to indicate g729A.  You just have to use g729.
> The reason for lack of g729a in RFC 3550 is that g729 and g729a
> should interoperate seemlessly - as it says...
>
>
> Regards,
>
> Attila
>
>
> Hi,
>        Please let me know if "rtpmap:18 G729a/8000" is a wrong format.
>
> I guess RFC3551 says it should work (page 19, as pasted below) and I am
> not able to find anything so specific in RFC3550.
>
>
>
> Thanks & Regards
> Viresh Gupta
>
>
>


-- 
Regards
Harsha
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