Microsoft Lync and Skype for Business platforms do the '183 w/SDP-then-180 response to INVITE' all the time.
When I worked with AcmePacket SBCs, and connecting to MSFT platforms to PSTN/carrier, for inbound calls we had the SBC change any 183 response to 180 and delete the SDP before sending the response to a PSTN connection. That way the PSTN only sees 180, and ringback generation from the originating side continues. On Tue, Aug 20, 2019 at 9:37 AM Pete Eisengrein <[email protected]> wrote: > We have recently gotten several complaints about not getting, or severely > abbreviated ringback. The first few examples we were able to trace back to > a carrier and believe it is because the call sets up with 183 Session > Progress w/SDP and <1 second later get a 180 Ringing and the audible > ringing stops. > > We heard a similar complaint in Europe last with an EU carrier. And again > today with yet another US (global) provider. > > So, my questions are: > > 1- Anyone else seeing this? If so, what's your workaround/fix? > 2- Since this is not contained to a single carrier, anyone aware of an SBC > or softswitch maker recently released code that might be causing? > > Thanks, > Pete > _______________________________________________ > VoiceOps mailing list > [email protected] > https://puck.nether.net/mailman/listinfo/voiceops >
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