I have done that before, and I'm sorry, but it becomes a time-sink-hole. Getting the phone simply set up to use Google Voice is easy, but mastering the nuances of OBi settings is not.
You'd have to first have a good understanding of how Google Voice works (nevermind on an OBi).
Some people are misled into thinking that Google Voice is just a "free telephone company", and it is certainly not that.
If you want to ask some basic questions and you are already comfortable using Google Voice on its website (
https://voice.google.com/) and on an Android or iPhone, then I can help you.