Hello All, I come with hopes and prayers you may be able to assist me with this. I currently have a 3CX setup with 1 local and 1 remote extension. Both phones are running 8-5-4S versions of the SIP firmware. After a lot of troubleshooting and testing I was finally able to get the remote extension to register. However the reliability of the connection and what works is very inconsistant. For example when making a call out the remote extension worked with no issues. When we test called a line coming in, local phone worked however the line did not ring on the other end. Looking in the log I do get this. 14/04/2017 03:03:57:706 | Call to T:Extn:101@[Dev:sip:email@example.com:5061;transport=udp] from L:67.1[Extn:100] failed, cause: Cause: 404 Not Found/INVITE from xxx.xxx.xxx.xxx:49389 On the remote end we have forwarded ports 5060, 5061, 9000-9500 as well. When trying to dial the extension of the remote phone I get a fast busy signal and Reorder on the bottom of the screen. It just doesn't connect. Now we did have a few times where the remote extension did in fact dial to the local extension. However when hanging up and trying again it wouldn't connect again. Using the 3CX log viewer I do not see the actual connected call. Which is odd as I would think it'd be in here. I do see the call in the call log in the dashboard though. We were able to make 3 calls and it now no longer works. So I'm unsure what allowed them to at first but will not do it now. This right here I believe might be the call coming in, however the INVITE I'm not sure is right. 14/04/2017 03:04:49:423 | [CM503003]: Call(C:72): Call to <sip:firstname.lastname@example.org:5060> has failed; Cause: 487 Request Terminated/INVITE from 127.0.0.1:5488 I have tried disabling and enabling the options for: PBX Delivers Audio is On Allow Remote Extensions Outside of LAN Settings for Direct SIP calls - Currently Unchecked. Send Media to IP and port of REGISTER - checked Enable Keep Alives 30 - Checked Firewall check on my end does show all green. On the remote end if I use a port checker I do get port not open for 5060, 5061 and 9000-9500(any random port I choose). Anyone able to offer some insight as to if this is on the 3CX end or is it on the Remote end? We've DMZd the phone IP as well thinking something might of been blocking it on that end but that didn't seem to make a difference. I am running a pfsense firewall in front of the 3CX server if that helps, the remote location just uses there dsl router from the company. I forget the company off hand. Thanks in advanced!