I am experiencing the same problem on my OBI202 v3.2.2 (Build: 5898EX) configured with Google Voice. Calls may be made to and from the OBI but no audio and call drops after 15 seconds or so. My call stats look the same as yours. I have also tried SteveInWa's advice to remove and remount the OBI (many times) as well as all of the following but still have no audio.
1) Put OBI on DMZ on Router.
2) Skipped router and plugged OBI directly into the hub that feeds our house (we are on a school campus) with only one phone.
2) Transfered GV number to another account and updated GV credentials on OBITalk as advised in post
http://www.obitalk.com/forum/index.php?topic=14643.03) Reverted to Firmware 5859EX (after turning off auto update via Web interface).
OBI behaves the same every time. Rings or calls ...no audio...drops call. I am stumped.
Any ideas of other paths to try. This OBI has been a great box for us and worked well until just a few days ago.