Here is my setup:
3CX on Debian linux on a static IP on my LAN
External SIP providers out on internet
All sip phones on same LAN as the 3CX
I have previously run PBXs behind the Edgemax with no ports open, and the connection to my VOIP provider has succeeded with no issues, so I assume the "related" packets were keeping this open
Now that I have switched to 3cx, I have GUI based port-forwarding enabled for the requested ports of 5060 and 9000-9010 to my 3cx server ip address on the LAN. ( I assume the firewall though is opening to the world...)
When my server is rebooted, outgoing calls work fine, but incoming calls get a busy signal.
Now, the weird part...They all strart working as soon as I make an outgoing call on one of the phones or I run the built in 3CX firewall checker, which tests open ports.
It seems like the EdgeMax is having trouble dirceting those first incoming packets through into the NAT
1. Any way to prevent this or what the issue is?
2. Do these ports have to be port forwarded?
3. What is easist way to whitelist only my VOIP providers?