I am having the same issue with Obi202. It replaced an Obi100, which my faxing worked flawlessly via my Brother AIO, now I experience the same, where the responding party sends out its initial handshake tones, and then the audio gets cut-off while my fax keeps emitting the hello tones. Never did anything with codecs or settings on the Obi100 it just plain worked via GV and lowering speed setting on the AIO.
I can't believe that the cheaper Obi100 seems to be less problematic than the Obi 202, this is now my second issue with this 'business' class model. I used to be an Obi evangelist and have installed several overseas, but now not getting a good vibe...
EDIT: Got it to successfully send to my Efax number as a test via GV after 2nd dial attempt, by disabling the T38Enable setting on the Obi202, that is unchecking the checkbox. One less issue to contend with and confidence rebuilding...