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, <[email protected]> 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 > * [email protected] > 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 >
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