I just checked at 21:15 PST, and all of my 6 OBiTALK-managed devices show online. Perhaps it's just some temporary cosmic swamp gas thing with your account. I wouldn't worry about it for now, as long as the devices work for you. There have also been quite a few brief outages on the portal in the past, that get resolved the next day.
OBiEXTRAs is definitely not required to use the OBis with Google Voice. You took all the correct, necessary steps. Good luck!