Hi Mark,
Well, first of all, let's hope one of the experts on ObiTalk (like MichiganT) come along and help us out. They know far more about the ObiTalk portal than I.
Next, I find it puzzling that your Auto-Provisioning was disabled from the factory. I really thought the OBIs came with Provisioning enabled by default. It makes me wonder if some other extraneous settings may be amiss in your OBI. I don't know how much info you've programmed into the OBI; otherwise, I wonder if a hardware reset and then re-configuration may help... merely from a 'starting with a clean slate' perspective.
For router/firewall concerns, you could try temporarily placing the OBI in direct connection with the DSL modem (i.e. removing the router completely from the setup temporarily) and see what happens. Or, if your router supports a DMZ option, you could try to temporarily place the OBI in that zone. Since you are using SBCYahoo DSL, I wonder if bridging the modem with the router would help for the router/firewall concern. [Regarding your concerns about the router/modem, I noticed you mentioned D-Link. I believe others in this forum have disabled the SIP ALG feature in some of the D-Link routers for more successful traversal of SIP through the router. Although I am told that GV does not use SIP, and I doubt that ObiTalk does either, if you see the SIP ALG setting in the D-Link, you might consider disabling for general voip issues.]
Finally, I forget the exact method, but if you can re-register the device from within the ObiTalk portal, that's just one more thing to check.
Keep us posted,
pc44