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 <peeip989 at gmail.com> 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 VoiceOps at voiceops.org https://puck.nether.net/mailman/listinfo/voiceops