I set up GV. GV forwards to OBI 110 just fine. I chose in setup to make GV my outgoing provider under "Make This the Primary Line to Call Out from".
I get a stuttering dial tone. I dial a number. I get this: "there is no service available to complete your call."
And, yes, I have successfully made test calls from GMail, using the same Google account.
Try dialing **1 and the number. If that doesn't work, dial **2 and the number.
I suspect with your playing between GV and Callcentric (and your other posts) that you have some things a bit messed up in your setup.
And the stuttering dial tone is a message from GV. You need to read the documentation. ;)