It sounds like an FX-T or FX-S. He/she can go to the back of it and look at the cards, they all should have part numbers on them, list them here and we can tell you....that is the easiest way. By the way, both of those models are discontinued, it might be prudent to upgrade to the FX-II. You can re-use the cards and telephones in the FXT/S cabinet and be in supported hardware.

Steve