I have two systems... A 500 and a new 7100.
I have them linked via SPNet. If the 7100 calls the 500 everything is fine. If a caller from the 500 calls the 7100 the 7100 user cannot hear the 500 user but the 500 user can hear the 7100 user.

Ip phones work fine from the outside from both locations. Theses two systems are out on the Public directly plugged into a Comcast connection.

I put the two systems in the same room plugged them into a local switch and was fine.

Any ideas?