We have an AT&T Opteman (10MB) circuit connecting two of our buildings. A 5200 PBX is the only thing using this circuit at the moment. We've yet to move our operations. There are nine phones in our main building programmed to this switch. I will occasionally receive an insufficient bandwidth error. All nine phones are dropped.

I want to say it is the Opteman circuit, but I'm having trouble proving it. Any ideas?