[SIPForum-discussion] Codecs in 200 OK response

[Stephen James]

The offerer can then choose based on "local policy" to decide which codec to use.
My convention the preferred codec is listed first, so in the example provided the offerer would use G.711.


It is entirely possible at that point for a reINVITE to be sent settling on a single codec. (This I have seen as well).


Just to reiterate, the answered responding with multiple codecs is unusual, but not incorrect. 


Stephen James 
sjames_1958 at yahoo.com
 
We are not princes of the earth, we are the descendants of worms, and any nobility must be earned.



________________________________
 From: pradeep gali <pradeepgali30 at gmail.com>
To: "Mirchandani, Pushpa" <Pushpa.Mirchandani at charter.com> 
Cc: Stephen James <sjames_1958 at yahoo.com>; Waqas Arshad <waqas.arshad000 at yahoo.com>; "discussion at sipforum.org" <discussion at sipforum.org> 
Sent: Monday, October 14, 2013 2:02 PM
Subject: Re: [SIPForum-discussion] Codecs in 200 OK response
 


Pushpa,

Usually INIVITE will send multiple codecs Saying"These are the supported codecs from my side" and the for end device choose any one codec which is supported by that device and sends 200 OK with single Codec and the media will establish with that selected codec. 
 So, the device who is sending 200 OK will decide which codec to use. 




On Wed, Oct 9, 2013 at 3:33 PM, Mirchandani, Pushpa <Pushpa.Mirchandani at charter.com> wrote:

Would you use primary and secondary choice? For example always use G.711 first ? Thanks 
> 
> 
>Pushpa
> 
> 
> 
>From:discussion-bounces at sipforum.org [mailto:discussion-bounces at sipforum.org] On Behalf Of Stephen James
>Sent: Monday, October 07, 2013 1:15 PM
>To: Waqas Arshad; discussion at sipforum.org
>Subject: Re: [SIPForum-discussion] Codecs in 200 OK response
> 
>Yes the reponse to an INVITE can contain more than one codec. This means that the answerer can receive more than one codec type during the call.
>In our system we implemented specific behavior to force our system to send only 1 codec in the answer.
> 
> 
>Stephen James 
>sjames_1958 at yahoo.com
> 
>We are not princes of the earth, we are the descendants of worms, and any nobility must be earned.
> 
>
>________________________________
>
>From:Waqas Arshad <waqas.arshad000 at yahoo.com>
>To: "discussion at sipforum.org" <discussion at sipforum.org> 
>Sent: Monday, October 7, 2013 2:39 AM
>Subject: [SIPForum-discussion] Codecs in 200 OK response
> 
>Hi,
> 
>Can someone please confirm if the SDP of 200 OK (in response to an INVITE) can contain multiple codecs in m-line or it should have only one codec at which B party has responded to establish the connection. e.g.
> 
>INVITE SDP:
>m=audio 39838 RTP/AVP 0 8 18 101
>a=rtpmap:0 pcmu/8000
>a=rtpmap:8 pcma/8000
>a=rtpmap:18 G729/8000
>a=fmtp:18 annexb=no
>a=rtpmap:101 telephone-event/8000
>a=fmtp:101 0-15
>a=sendrecv
> 
>200 OK SDP:
>m=audio 18238 RTP/AVP 0 101
>a=rtpmap:101 telephone-event/8000
>a=fmtp:101 0-15
>a=X-sqn: 0
>a=X-cap: 1 audio RTP/AVP 100
>a=X-cpar: a=rtpmap:100 X-NSE/8000
>a=X-cpar: a=fmtp:100 200-202
>a=X-cap: 2 image udptl t38 
> 
>So can 200 OK SDP contain m-line as below too or just one codec at which call is going to be established???
> 
>m=audio 18238 RTP/AVP 0 8 18 101
> 
>Secondly, can someone please suggest the meaning of a=X-sqn in above 200OK?
> 
>Thanks in advance.
>Waqas
>
>_______________________________________________
>This is the SIP Forum discussion mailing list
>TO UNSUBSCRIBE, or edit your delivery options, please visit http://sipforum.org/mailman/listinfo/discussion
>Post to the list at discussion at sipforum.org
>
>
>_______________________________________________
>This is the SIP Forum discussion mailing list
>TO UNSUBSCRIBE, or edit your delivery options, please visit http://sipforum.org/mailman/listinfo/discussion
>Post to the list at discussion at sipforum.org
>
>


-- 
Pradeep Gali 
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://sipforum.org/pipermail/discussion/attachments/20131014/40eb77b1/attachment-0002.html>