Question about early media - sr-users

Daniel-Constantin Mierla

5 Oct 5 Oct

10:48 a.m.

Hello, On 10/4/10 2:36 PM, Asim Riaz wrote:

Hi List, Phone-1 ------->Proxy1 (kamailio)-------------->Proxy-2(3rd party) -------------> phone 2 Calls from phone-1 to phone-2, proxy-2 is sending early media without sdp in provisional reply, this early media is sourced from different port than response (200), what port proxy-1 will use to transmit actual voice, the source port in early media or source port in response(200) which is different than early media.

kamailio is not relaying media - you can use rtpproxy together with it to do that. Cheers, Daniel -- Daniel-Constantin Mierla http://www.asipto.com

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Iñaki Baz Castillo

7:14 p.m.

2010/10/4 Asim Riaz <ariaz78(a)gmail.com>om>:

...

Hi List, Phone-1 ------->Proxy1 (kamailio)-------------->Proxy-2(3rd party) -------------> phone 2 Calls from phone-1 to phone-2, proxy-2 is sending early media without sdp in provisional reply, this early media is sourced from different port than response (200), what port proxy-1 will use to transmit actual voice, the source port in early media or source port in response(200) which is different than early media.

As Daniel said Kamailio doesn't handle media (it's a SIP proxy). You should mean "Phone-1" instead of "proxy-1". According to the RFC about SDP (and also RFC 3261): during the same early dialog (same To-tag) the SDP MUST NOT change. This is, if a UAS generates a 183 (To-tag=1234) with SDP, it MUST use the same SDP in other 183's responses and in final 200 OK response. The client can receives multiple SDP (when there is a proxy doing parallel forking, but each early dialog (same To-tag) MUST mantain a fixed SDP. So, if the client receives a different SDP in the 200 than the SDP it received in the 183 (I mean in the *same* early-dialog / same To-tag) then the client MUST ignore others SDP but the first one received. I insist: I'm speaking about the SDP in the SAME early-dialog. -- Iñaki Baz Castillo <ibc(a)aliax.net>

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Asim Riaz

7 Oct 7 Oct

4:53 p.m.

Thanks for the input, proxy-2 which is 3rd party sending early media without SDP info in pregress message(180 or 183). On Tue, Oct 5, 2010 at 7:47 PM, Andreas Heise <aheise.lists(a)googlemail.com>wrote;wrote:

...

Hello, you could change the SDP with UPDATE method, but 183 must be send reliable in this case. regards, Andreas 2010/10/5 Iñaki Baz Castillo <ibc(a)aliax.net>

2010/10/4 Asim Riaz <ariaz78(a)gmail.com>om>:

Hi List, Phone-1 ------->Proxy1 (kamailio)-------------->Proxy-2(3rd party) -------------> phone 2 Calls from phone-1 to phone-2, proxy-2 is sending early media without

sdp in

provisional reply, this early media is sourced from different port than response (200), what port proxy-1 will use to transmit actual voice, the source port in early media or source port in response(200) which is different than early media.

As Daniel said Kamailio doesn't handle media (it's a SIP proxy). You should mean "Phone-1" instead of "proxy-1". According to the RFC about SDP (and also RFC 3261): during the same early dialog (same To-tag) the SDP MUST NOT change. This is, if a UAS generates a 183 (To-tag=1234) with SDP, it MUST use the same SDP in other 183's responses and in final 200 OK response. The client can receives multiple SDP (when there is a proxy doing parallel forking, but each early dialog (same To-tag) MUST mantain a fixed SDP. So, if the client receives a different SDP in the 200 than the SDP it received in the 183 (I mean in the *same* early-dialog / same To-tag) then the client MUST ignore others SDP but the first one received. I insist: I'm speaking about the SDP in the SAME early-dialog. -- Iñaki Baz Castillo <ibc(a)aliax.net> _______________________________________________ SIP Express Router (SER) and Kamailio (OpenSER) - sr-users mailing list sr-users(a)lists.sip-router.org http://lists.sip-router.org/cgi-bin/mailman/listinfo/sr-users

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