I'm having a problem with conferencing remote IP phones. I have an 8-port card with 2 modules on it and 3 extensions programmed. The customer is complaining that the audio is real choppy and distorted when they conference these extensions. I tested last week with 2 of the three and all worked fine. Today I went back and sure enough it did not work. As I was calling each individual extension the audio was clear but once I conferenced all of them together it was impossible to carry on a conversation. Could this be a problem with the IP card? Or would it be a problem somewhere else?

Its caused by network latency...ever tried calling a cell that is in the same room? The timing is a bit off...VOIP suffers from this a lot.

Yep I know about Latency. That's not what this is. As I mentioned before when I call the individual extensions the audio is fine. It's only when I add them to the conference that the audio goes in the dumper. Any other ideas how to troubleshoot this?

I reread your OP and discovered I missed something. You are a port short. Try conf a digital phone with any TWO ip phones and I bet the audio is just fine, go to three or two with the third off hook and talking to someone and it distorts because you need one port per active phone.