Just wanted to put this out there. I've stated using Google voice again as my SP. I finally got it working again except I noticed the message waiting indication/stutter tone was no longer working. When I contacted Obihai support the answer I received was "The vmail indicator (either light or stuttered tone) is no longer a feature that is supported on the OBi with Google Voice. You would need to check your gmail or hangouts to find out if there is voicemail pending." This is fine for me because I get a email when I have voice mail on Google, but I thought I would share in case anyone was wondering.
This has already been discussed and confirmed in several other threads.
Thanks for sharing i was wondering the same. As too why it was not working.