Hi:
I think you've tried a lot of things, but a more systematic approach to troubleshooting would be helpful.
You've apparently confirmed that the OBi is successfully connecting to the internet by placing a OBiTALK network call to it. That's a good sign.
Your problem is still vague, however. I'd start over from scratch, by deleting your OBi off of the OBiTALK portal, factory resetting it, adding it back to the portal again, and setting up Google Voice again as the service provider.
Before reviewing my instructions at the link below, you may want to "fast track" to these two possibilities: 1) you are logged into the wrong Google account on the OBi (different from the one that holds your GV phone number) or 2) you don't have Google Chat added as a forwarding destination on the GV account you're using.
See:
http://www.obitalk.com/forum/index.php?topic=8560.msg56460#msg56460OH, and one other thing: 911 service: you
do know that GV does not support 911 calling, right? You must establish separate 911 service with another provider, like Anveo or Callcentric.