Re: [SR-Users] Manage multiple RTP streams with different TO-tags (forking)

Hi, I faced a quite same situation recently and I have asked on RTPEngine Github: https://github.com/sipwise/rtpengine/issues/1330 Your scenario is a bit different but with the workaround described in the issue (overriding to-tag flag in rtpengine request), maybe you can fix your issue. Just also be careful when either Alice or Bob sends ReInvites within the call, to-tag (or from-tag depending on who sent the request) will need to be overridden too. Julien *De : *sr-users &lt;sr-users-bounces(a)lists.kamailio.org&gt; au nom de Arsen Semenov &lt;arsperger(a)gmail.com&gt; *Répondre à : *"Kamailio (SER) - Users Mailing List" < sr-users(a)lists.kamailio.org&gt; *Date : *vendredi 27 août 2021 à 07:28 *À : *"Kamailio (SER) - Users Mailing List" &lt;sr-users(a)lists.kamailio.org&gt; *Objet : *Re: [SR-Users] Manage multiple RTP streams with different TO-tags (forking) it's legal to get responses with different to-tags, since the request is forked. this is what's happening in this scenario. I think this is an issue of UAC/rtpengin how it is reacting to the second SDP in 183 are the SDPs in 183 responses carried reliably? On Fri, Aug 27, 2021 at 2:51 PM Yuriy Gorlichenko &lt;ovoshlook(a)gmail.com&gt; wrote: Hello. The first thing: to tag can't be changed due session once it passed. If provider uses forking mechanism the it has to be hidden from your system. Regarding SDP according https://datatracker.ietf.org/doc/html/rfc3261#section-13.2.1 They can't change SDP answer description on the fly. Only first SDP answer used as proper, all othe answers will be ignored. On Fri, 27 Aug 2021, 11:27 B. Tietz, &lt;benjamin.tietz(a)berlin.de&gt; wrote: Hello, following situation. I have a Kamailio (5.4) using rtpengine to loadbalance calls. If a call from Alice comes in, Kamailio decides to send the call to Carrier B from Bob. Bobs Phone is ringing and the carrier B send a 183 Session Progress with SDP and To-tag=abcd. The SDP has G722 as codec and port 1234. A few moments later carrier B send a second 183 Session Progress with SDP and TO-tag=fghi. The SDP has G711 as codec and port 5678. This is done, to play some funky music as ringtone -.- If Bob answers the call, carrier B sends a 200 OK WITHOUT SDP and TO-tag=abcd. So this should instruct our Kamailio to switch to the first G722 and port 1234. But sadly, this is just not working as expected. We tried to set the flags media-handover and port-latching for the rtpengine options and additionally set a to-tag when using rtpenging_manage. But this doesn't solve the codec change, so we have only audio when Bob answers the call, but no ringtone-music. If we allow G711 only in the outgoing INVITE to Bob, we have also tha ringtone-muisic, because there is no codec-change. Carrier B tells us, they are using a fork-mechanism. Is there something we can do, to support the codec change in 183? Or enforce carrier B to send SDP in 200 OK? Or anything else? Carrier B can not change anything in the ringtone-music-backend. They are stuck on G711. Thanks! __________________________________________________________ Kamailio - Users Mailing List - Non Commercial Discussions * sr-users(a)lists.kamailio.org Important: keep the mailing list in the recipients, do not reply only to the sender! Edit mailing list options or unsubscribe: * https://lists.kamailio.org/cgi-bin/mailman/listinfo/sr-users __________________________________________________________ Kamailio - Users Mailing List - Non Commercial Discussions * sr-users(a)lists.kamailio.org Important: keep the mailing list in the recipients, do not reply only to the sender! Edit mailing list options or unsubscribe: * https://lists.kamailio.org/cgi-bin/mailman/listinfo/sr-users -- Arsen Semenov __________________________________________________________ Kamailio - Users Mailing List - Non Commercial Discussions * sr-users(a)lists.kamailio.org Important: keep the mailing list in the recipients, do not reply only to the sender! Edit mailing list options or unsubscribe: * https://lists.kamailio.org/cgi-bin/mailman/listinfo/sr-users