Voipgo and Nokia E65

I have a Nokia E65 and recently signed up for Voipgo's service. Customer service has been great but they haven't figured out how to solve my problem. I am not able to get the phone to register the SIP settings... Does anyone know what I can do? Customer service said that it may be the firmware that it doesn't have a STUN server or something like that, but I don't know... Thanks in advance