In light of an issue that appears to be effecting multiple people, myself included, I was wondering if anyone on the latest version has been able to successfully have incoming calls with more than one IP Based authentication SIP trunk or VOIP provider at the same time? I think it would help prioritize this issue if it can be noted it is effecting all users. It appears for myself and others that a bug exist where whenever an IP authenticated SIP trunk is modified, it causes all other IP authenticated based SIP trunks to have all incoming calls reported by the PBX as Proxy Auth Required. If you go into these trunks that are now reporting this error and "edit" them, then back out, they now can take incoming calls without reporting this, however the other IP authenticated SIP trunks in the system now report Proxy Auth as well. For more details on this issue being reported, here are a few posts. https://www.3cx.com/community/threads/v15-incoming-issues-with-multiple-trunks.47430/ https://www.3cx.com/community/threa...trunk-breaks-other-sip-trunk-everytime.47339/ Possibly related below, user didn't mention running a wireshark but switched from User ID to IP based SIP reg and had issues with multiple trunks. https://www.3cx.com/community/threads/multiple-dids-via-vitelity-via-ip-non-registration.46872 ********UPDATE/WORKAROUND*********** 3CX provided a workaround for the issue. See post below. You will have errors in your 3CX log with this workaround, and they will show as red trunks / unregistered, but the calls are working.