Get a pc/laptop set up Hyper Terminal,you might have to try a few different port settings, 9600,4800,2400,1200 8,n,1 ( even 7,e,1 sometimes) then take the serial lead from your server com port and connect into your com port and make some calls in and out and see what you get, at least this way you can pinpont the fault, if nothing appears after a call check com settings.
