Hi:
In fact, Google Voice is not like a regular land line, and GV isn't a regular telephone carrier.
The best way to troubleshoot this is to isolate whether the problem is on the Google side, or something specific to your OBi setup.
Unplug your OBi from power. Log into your Gmail (not Google Voice) account, using the same user name as you are using on your OBi. Assuming that you are either using Google Chrome Browser, or MS IE, Safari or Firefox with the Google voice and video plugin installed, click on your chat avatar on the left middle side of the Gmail page (the generic head and shoulders, or a photo you may have uploaded). If you have upgraded your account to use Google Hangouts, then look at the bottom of the Hangouts setting box for the small link "Revert to old Chat" and click it. Otherwise, use Chat to make several different outbound phone calls to various different phone numbers, and take note of what happens.
Do you experience the same issues, or do the calls promptly answer?
What type of numbers are these? Are you calling residential land lines, cell phones, or businesses with some sort of IVR (Interactive Voice Response) system, or answering service, or a toll-free number, or a so-called "free" conference service?