I have a Obi200 and I'm having the same problem. It is VERY frustrating!!!
It's been working for 2 years, but now when someone calls, I get "Incoming Call' and one ring and then nothing. Not even a Caller ID to know who's calling. The caller gets a message "Voicemail hasn't been setup". If I go to the Google Voice screen, it does show who called.
My account is linked to Callcentric DID for e911 calls, my cell phone, and Hangouts. Do Not Disturb is OFF. Calls are also forwarded to Callcentric and my cell phone, and screen calls is ON.
I just want my phone calls to go to my house phones again.