I have a UCM6204 configured at our office, working with phones on the LAN.
I’m now trying to connect a GXP2140 phone from a home office.
I’ve enabled port forwarding on our office firewall to forward tcp/udp 5060 and 5061 to the UCM.
I’ve enabled a static (public internet) IP on our firewall for the UCM, and configured that IP under PBX -> SIP Settings (NAT) as the “external host” IP address.
I’ve configured the GXP2140 to point to the UCM’s IP address.
Thus far I have been unable to get the phone to connect.
I’ve tried using a couple of public STUN servers, but that also has not helped.