So we are having an issue with a new install and the SIP provider (Intelepeer) believes it's on the 3cx side or the router side. We have another PBX (different software) setup behind the same router using the same trunk provider without this problem, so I'm leaning more towards the 3CX side. Hoping there is a fix for it in some settings that I can't find. The issue is we have a SIP trunk registered via IP address. We have the box checked "Put Public IP in SIP VIA Header" in order for it to register properly, which it does and we can make calls. Audio and calls are all working great. The one issue is when we have an incoming call that is answered, when the answering party hangs up, the BYE message they send gets rejected by the SIP trunk provider due to the SIP VIA header has the private IP, not the public. This does not happen with the other PBX software we are currently using. It puts the public IP in the BYE message VIA: SIP header. Below is what the SIP trunk provider is saying the issue is (the yellow part). Is this a bug or never had much a need to be addressed? I've rebuilt the trunk several times, same issue. If I use a different trunk provider that we register with (non-ip based) they don't care about the BYE message having the local IP in the VIA header and accept it. My understanding though is IP based authentication sip trunks needs this to match to not reject it. Anyone have a work around for this or some setting that is being missed?