[SIPForum-discussion] What's the info contained in the SDP?

[devibalas sdevibala]

Hi Mike,
   As far as ur call is concerned the SDP info can either be carried in 180
ringing or in 200OK. The SIP server will send back the SDP info of the
called party(B) to the calling party(A). The server either has this info
stored(Purely IP) or if the called party  is connected to a CODEC/GW then it
uses MEGACO protocol to create a session get the SDP info & passes it on to
the calling Side.

Rgds,
DBS



On Mon, Jul 13, 2009 at 9:43 PM, Mike Jiang
<mike.jiang at andersontaylor.com>wrote:

>    Hi, All
>
>       I have a quick question: when I make a call from a SIP phone, the SIP
> server sends 183 Session Process, 180 Ringing, and 200 OK msgs sequentially
> back
>
>  to the phone. Usually at least one of three above has the SDP as the
> body. The SDP contains the info about the IP, port, and audio codecs of the
> target. My question is: is the IP/port that of the SIP Server or the
> callee’s phone? The reason why I ask this is: the SIP phone only talks with
> the SIP server directly, then the SIP server manages to relay voice packets
> to the callee. As for how the SIP server routes the call to the callee,
> that’s not the business the SIP phone cares.  So I think the IP/Port in SDP
> is that of the SIP server rather than the callee’s phone. The SIP server
> provider told me it’s the callee’s. I got confused.
>
>
>
>       Thanks for any input,
>
>
>
>       Mike J.
>
>
>
>
>
>
> __________ Information from ESET NOD32 Antivirus, version of virus
> signature database 3832 (20090206) __________
>
> The message was checked by ESET NOD32 Antivirus.
>
> http://www.eset.com
>
> _______________________________________________
> 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
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://sipforum.org/pipermail/discussion/attachments/20090714/a85b4906/attachment-0002.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image001.gif
Type: image/gif
Size: 145 bytes
Desc: not available
URL: <http://sipforum.org/pipermail/discussion/attachments/20090714/a85b4906/attachment-0002.gif>