<div dir="ltr"><div>I did have a very similar problem and it got solved by using the via-branch=auto in the rtpengine offer....</div><div>Check the comments here: <a href="https://github.com/sipwise/rtpengine/commit/23977237c0753c9877b082d71d45348387ad1606">https://github.com/sipwise/rtpengine/commit/23977237c0753c9877b082d71d45348387ad1606</a></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Fri, 27 Aug 2021 at 21:40, Julien Klingenmeyer <<a href="mailto:julien.klingenmeyer@ovhcloud.com">julien.klingenmeyer@ovhcloud.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
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<p class="MsoNormal"><span>Hi,<u></u><u></u></span></p>
<p class="MsoNormal"><span><u></u> <u></u></span></p>
<p class="MsoNormal"><span lang="EN-US">I faced a quite same situation recently and I have asked on RTPEngine Github:
<a href="https://github.com/sipwise/rtpengine/issues/1330" target="_blank">https://github.com/sipwise/rtpengine/issues/1330</a><u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US">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.<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US"><u></u> <u></u></span></p>
<p class="MsoNormal"><span lang="EN-US">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.<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US"><u></u> <u></u></span></p>
<p class="MsoNormal"><span lang="EN-US">Julien<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="EN-US"><u></u> <u></u></span></p>
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<p class="MsoNormal"><b><span style="font-size:12pt;color:black">De : </span></b><span style="font-size:12pt;color:black">sr-users <<a href="mailto:sr-users-bounces@lists.kamailio.org" target="_blank">sr-users-bounces@lists.kamailio.org</a>> au nom de Arsen Semenov <<a href="mailto:arsperger@gmail.com" target="_blank">arsperger@gmail.com</a>><br>
<b>Répondre à : </b>"Kamailio (SER) - Users Mailing List" <<a href="mailto:sr-users@lists.kamailio.org" target="_blank">sr-users@lists.kamailio.org</a>><br>
<b>Date : </b>vendredi 27 août 2021 à 07:28<br>
<b>À : </b>"Kamailio (SER) - Users Mailing List" <<a href="mailto:sr-users@lists.kamailio.org" target="_blank">sr-users@lists.kamailio.org</a>><br>
<b>Objet : </b>Re: [SR-Users] Manage multiple RTP streams with different TO-tags (forking)<u></u><u></u></span></p>
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<p class="MsoNormal"><u></u> <u></u></p>
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<p class="MsoNormal">it's legal to get responses with different to-tags, since the request is forked. this is what's happening in this scenario.
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I think this is an issue of UAC/rtpengin how it is reacting to the second SDP in 183<u></u><u></u></p>
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<p class="MsoNormal"><u></u> <u></u></p>
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<p class="MsoNormal">are the SDPs in 183 responses carried reliably?<u></u><u></u></p>
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<p class="MsoNormal"><u></u> <u></u></p>
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<p class="MsoNormal">On Fri, Aug 27, 2021 at 2:51 PM Yuriy Gorlichenko <<a href="mailto:ovoshlook@gmail.com" target="_blank">ovoshlook@gmail.com</a>> wrote:<u></u><u></u></p>
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<p class="MsoNormal">Hello. <u></u><u></u></p>
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<p class="MsoNormal">The first thing: to tag can't be changed due session once it passed.<u></u><u></u></p>
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<p class="MsoNormal"><u></u> <u></u></p>
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<p class="MsoNormal">If provider uses forking mechanism the it has to be hidden from your system. <u></u><u></u></p>
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<p class="MsoNormal"><u></u> <u></u></p>
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<p class="MsoNormal">Regarding SDP according<u></u><u></u></p>
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<p class="MsoNormal"><a href="https://datatracker.ietf.org/doc/html/rfc3261#section-13.2.1" target="_blank">https://datatracker.ietf.org/doc/html/rfc3261#section-13.2.1</a><u></u><u></u></p>
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<p class="MsoNormal">They can't change SDP answer description on the fly. Only first SDP answer used as proper, all othe answers will be ignored.<u></u><u></u></p>
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<p class="MsoNormal"><u></u> <u></u></p>
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<p class="MsoNormal">On Fri, 27 Aug 2021, 11:27 B. Tietz, <<a href="mailto:benjamin.tietz@berlin.de" target="_blank">benjamin.tietz@berlin.de</a>> wrote:<u></u><u></u></p>
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<p class="MsoNormal">Hello,<u></u><u></u></p>
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<p class="MsoNormal"><u></u> <u></u></p>
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<p class="MsoNormal">following situation.<u></u><u></u></p>
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<p class="MsoNormal">I have a Kamailio (5.4) using rtpengine to loadbalance calls.<u></u><u></u></p>
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<p class="MsoNormal"><u></u> <u></u></p>
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<p class="MsoNormal">If a call from Alice comes in, Kamailio decides to send the call to Carrier B from Bob.<u></u><u></u></p>
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<p class="MsoNormal">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.<u></u><u></u></p>
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<p class="MsoNormal">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 -.-<u></u><u></u></p>
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<p class="MsoNormal">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.<u></u><u></u></p>
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<p class="MsoNormal"><u></u> <u></u></p>
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<p class="MsoNormal">But sadly, this is just not working as expected.<u></u><u></u></p>
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<p class="MsoNormal"><u></u> <u></u></p>
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<p class="MsoNormal">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.<u></u><u></u></p>
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<p class="MsoNormal">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.<u></u><u></u></p>
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<p class="MsoNormal"><u></u> <u></u></p>
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<p class="MsoNormal">Carrier B tells us, they are using a fork-mechanism.<u></u><u></u></p>
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<p class="MsoNormal"><u></u> <u></u></p>
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<p class="MsoNormal">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?<u></u><u></u></p>
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<p class="MsoNormal"><u></u> <u></u></p>
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<p class="MsoNormal">Carrier B can not change anything in the ringtone-music-backend. They are stuck on G711.<u></u><u></u></p>
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<p class="MsoNormal"><u></u> <u></u></p>
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<p class="MsoNormal">Thanks!<u></u><u></u></p>
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<p class="MsoNormal">__________________________________________________________<br>
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<p class="MsoNormal"><br clear="all">
<u></u><u></u></p>
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<p class="MsoNormal"><u></u> <u></u></p>
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<p class="MsoNormal">-- <u></u><u></u></p>
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<p class="MsoNormal">Arsen Semenov<u></u><u></u></p>
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<p class="MsoNormal"><u></u> <u></u></p>
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