GV calls dropping after ~10 mins

[tv2k]

Anyone experience GV calls dropping after 10 mins +- a few seconds?
I have an OBi 110 with GV on SP1 and CallWithUs on SP2.

I have tested the following.
1. Android ObiON -> OBi 110 -> GV (SP1): call drops after 10 mins
2. Cell phone -> GV (SP1) -> SP2 : call drops after 10 mins
3. corded phone on line port -> GV (SP1) -> cell : call was connected for over 1 hour.

I'll try 3 again to see if I can consistently get over 10 mins, but 1 & 2 are consistently dropping after 10 mins.  The 10 minute value is very suspicious.  It is plus/minis only 2 or 3 seconds from the Obi call log and shows up as an 11 minute call in GV.

Any clue on whether this is an issue with GV or the Obi?  Any idea on how to debug who is dropping the call?  Is there a log on the Obi that will indicate whether GV is dropping?

Is GV that unreliable.  I see many posts on the Google forums about dropped calls after a fixed time of 10 mins, 15 mins, or 30 mins.
http://groups.google.com/a/googleproductforums.com/forum/#!category-topic/voice/making-and-receiving-calls/RESNlu6SV3E

[jimates]

Dropped calls are usually router related.

google voice does seem to limit calls to 60 minutes sometimes. I don't usually have calls that long but my wife was on a training call once that was disconnected at exactly 60 minutes.