I have a VoIP card with some remote IP phones working on a public IP connection. Can I move the card behind a firewall using NAT or port forwarding?

I've never been successful in doing this and I don't believe I know of anyone who has either. We always put a small switch between the modem and the router and use a static IP address for the IP card. I was always told by technical support that "they don't handle NAT well". Translation: No, it can't be done. It is my understanding that this was addressed in later versions of XTS software, but I never saw it work.

Of course the phones can be connected to any network as long as the router configuration permits it.

Right,that was my thinking also. Putting the IP card inside the firewall was not supported. Just needed someone else to weight in on it. Thank You Ed.

We had a hardware VPN setup between sites and used it that way behind the firewalls as a few different sites over the years.\