System is SV9100.
We've had a lot of trouble with a remote IP phone. Bad connections, dropped calls, etc. I did a Wireshark capture at the remote end, and had NEC support look at it. They showed me where there is a public address trying to register to the phone's internal IP. After a lot of this, the phone crashes and reboots. They talked about port forwarding in the remote router to fix this.

The network guy says it wouldn't be port forwarding that is needed, but something in the router to block all traffic, except from the 9100's public address. And the cheap customer owned wireless router doesn't have that function.

Have I missed something all along that I should have done more setup on the remote end? Is the phone capable of doing this (only accepting traffic from the 9100)? Why would a remote IP phone do that anyway? Its only purpose is to communicate with the 9100, not anybody else on the internet.

Thank you.
Jim