Hi David,
What diagnostics does your setup give you? Does the BT101 register with Sipgate OK? Try a free softphone such as XLite or Zoiper to see what they do? Do you get one way audio/no audio/can't establish a call?
Looks like you may not be alone BTW:
http://community.virginmedia.com/t5/...ng/td-p/213327
http://community.virginmedia.com/t5/...io/td-p/885081
http://community.virginmedia.com/t5/...IP/td-p/174783