Some incoming calls not ringing

[Fasttimes]

I've had this setup for a while with CC for caller ID and just recently I've noticed many calls going to voicemail and not ringing at all.  I placed a few cell phone calls to verify this.  Sometimes it works, sometimes not.

While testing, I noticed a real outside call went to voicemail and they left a message.

Any ideas on how to solve this?  It's intermittent. 

[MikeHObi]

See this thread.  Issue appears to be a Google Voice issue.  No indication that they are working on resolving it yet.  There are some work arounds.
http://www.obitalk.com/forum/index.php?topic=6922.msg44322#new