We have done something very similar for a car dealership and another business that acquired a building across a public roadway. The PBX could support IP phones for the users and we used Multi-Tech VoIP adapters to extend dial tone to support fax and PA. It worked great for them.

I guess the trick for you is getting phones for the users on the remote end. I suppose you could "old school" it and install a small key system at the remote node and then emulate OPX with the VoIP gateways.

Bandwidth needed per call is minimal and, as long as the wireless is installed correctly and working well, this should be a perfectly viable option.

In case you are curious we have installed 2 sites using Proxim Tsunami wireless bridges and the appropriate Multi-Tech VoIP adapters. Equipment worked well but, until we had a clear grasp of the dial plan on the Multi-Tech, it was a bit of a challenge. We would overthink it. The Proxim was pretty much plug and play. ~ Mike

Michael Meyer