comments inline.
[EMAIL PROTECTED] wrote:
> Take a look to this scenario!
>
> A UAC sends an INVITE containing SDP like the following:
>
> v=0
> o=- 0 0 IN IP4 149.35.48.216
> s=SIP Call
> c=IN IP4 149.35.48.216
> t=0 0
> m=audio 5008 RTP/AVP 0 8 4 18
> a=rtpmap:0 PCMU/8000
> a=rtpmap:8 PCMA/8000
> a=rtpmap:4 G723/8000
> a=rtpmap:18 G729/8000
>
> The UAS respond with an OK containing the following SDP:
>
> v=0
> o=MxSIP 0 0 IN IP4 149.35.48.175
> s=SIP Call
> c=IN IP4 149.35.48.175
> t=0 0
> m=audio 5006 RTP/AVP 0 8
> a=rtpmap:0 PCMU/8000
> a=rtpmap:8 PCMA/8000
>
> The UAC start to send RTP packet using PCMU codec.
> The UAS start to send RTP packet using PCMA codec.
>
> Who are making a mistake?
The UAS. The offer-answer spec is fairly clear on this point:
In all cases, the codecs in the m line are listed in order of
preference, with the first codec listed being preferred. In this
case, preferred means that the recipient of the answer SHOULD use the
codec with the highest preference that is acceptable to it.
The UAS has violated the SHOULD by not using the codec with the highest
preference (codec 0).
-Jonathan R.
--
Jonathan D. Rosenberg, Ph.D. 72 Eagle Rock Avenue
Chief Scientist First Floor
dynamicsoft East Hanover, NJ 07936
[EMAIL PROTECTED] FAX: (973) 952-5050
http://www.jdrosen.net PH: (973) 952-5000
http://www.dynamicsoft.com
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