Obi using Google Voice has stopped ringing, but GV outbound calls work

[DieterProvisionen]

Is there a "troubleshooting tree" I should work through? 
Obi has been extremely frustrating ever since I switched to Callcentric when xmpp scare thing was going on.  GV wouldn't consistently forward calls to Callcentric, so when GV got officially supported, switched back to that.
Now having problems with Obi not ringing, though other phone (cell) rings via GV.

[SteveInWA]

Yes, start here:  http://www.obihai.com/faq/GV-and-the-OBi

[DieterProvisionen]

resolved, but thanks regardless. I'm managing obi's that I don't use myself so makes it more difficult, and in this particular case it was simply left on "do not disturb" ...ugh.  Enough trouble just troubleshooting GV anomalies and the ISP.