Thanks for the input, proxy-2 which is 3rd party sending early media without SDP info in pregress message(180 or 183).<br><br><br><br><div class="gmail_quote">On Tue, Oct 5, 2010 at 7:47 PM, Andreas Heise <span dir="ltr"><<a href="mailto:aheise.lists@googlemail.com">aheise.lists@googlemail.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">Hello,<div><br></div><div>you could change the SDP with UPDATE method, but 183 must be send reliable in this case.</div>
<div><br></div><div>regards,</div><div>Andreas</div><div><br><br><div class="gmail_quote">2010/10/5 Iņaki Baz Castillo <span dir="ltr"><<a href="mailto:ibc@aliax.net" target="_blank">ibc@aliax.net</a>></span><br>
<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"><div><div></div><div class="h5">2010/10/4 Asim Riaz <<a href="mailto:ariaz78@gmail.com" target="_blank">ariaz78@gmail.com</a>>:<br>
<div><div></div><div>> Hi List,<br>
> Phone-1 ------->Proxy1 (kamailio)-------------->Proxy-2(3rd party)<br>
> -------------> phone 2<br>
><br>
> Calls from phone-1 to phone-2, proxy-2 is sending early media without sdp in<br>
> provisional reply, this early media is sourced from different port than<br>
> response (200), what port proxy-1 will use to transmit actual voice, the<br>
> source port in early media or source port in response(200) which is<br>
> different than early media.<br>
<br>
</div></div>As Daniel said Kamailio doesn't handle media (it's a SIP proxy). You<br>
should mean "Phone-1" instead of "proxy-1".<br>
<br>
According to the RFC about SDP (and also RFC 3261): during the same<br>
early dialog (same To-tag) the SDP MUST NOT change. This is, if a UAS<br>
generates a 183 (To-tag=1234) with SDP, it MUST use the same SDP in<br>
other 183's responses and in final 200 OK response.<br>
The client can receives multiple SDP (when there is a proxy doing<br>
parallel forking, but each early dialog (same To-tag) MUST mantain a<br>
fixed SDP.<br>
<br>
So, if the client receives a different SDP in the 200 than the SDP it<br>
received in the 183 (I mean in the *same* early-dialog / same To-tag)<br>
then the client MUST ignore others SDP but the first one received. I<br>
insist: I'm speaking about the SDP in the SAME early-dialog.<br>
<font color="#888888"><br>
<br>
<br>
--<br>
Iņaki Baz Castillo<br>
<<a href="mailto:ibc@aliax.net" target="_blank">ibc@aliax.net</a>><br>
</font></div></div><div><div></div><div><br>
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