Hello, So I have 3CX V15 SP4 running on a machine (Win7 x64), no firewall issues, all necessary ports open, and I've changed 5060 and the HTTP/HTTPS ports over to others for security (in the high 50000's and early 60000's) and made all reflective changes (Windows Firewall Inbound Rule changes, router ports, etc etc) so the Firewall Test within 3CX passes and everything necessary is open. The entire system is now running perfectly, just as good as it was when using Elastix 4. Extensions set up, Yealink T42G phones provisioned (but not by PnP because this didn't work due to port changes probably - multicast didn't play ball). After my previous discussion regarding VOIP Gateways, we bought a Patton SN4112, hooked up the two hard lines, and inbound calls are now going to a chosen extension and everyone is able to ring out with a 9 prefix. All working fine! Very stable might I add for a first time 3CX user. Played around for hours with us ringing into the premises off our mobiles, colleagues taking calls, transferring around, playing with all aspects of the system. ....colleagues went home, we stopped playing with the phones, I got onto doing other things, and suddenly, at some point later when I did one last test to ring into the landline, the IP Phone wasn't ringing. The FXO line was blinking on the Patton Gateway which indicated somebody was ringing in, and it was also still connected to the PBX (LEDs solid green). But the call wasn't being routed to the IP Phone. Tried everything, restarted the machine, re-provisioned the IP Phone, factory restored the Patton and set the trunk up again from scratch to no avail. I had a think back to what I changed over the last couple hours after everyone went home and the only thing I could think was that I had installed Teamviewer on the server machine (to add it to our account for remote access). On the offchance I quickly uninstalled it and then tried to make a call in and hey presto, the call is being correctly routed, IP Phone is ringing again and everything is fine and dandy! Going to install Teamviewer again tomorrow evening to confirm that it was the issue but in the meanwhile has anybody else had something like this? Does it need to be investigated? I suspect it's tampering with something on the 3CX machine, either with the ethernet, a service, or there's a port issue. Thanks.