Okay, so it is backing off. No, I do not believe this has anything to do with the telephone you have plugged into the OBi. Backing off usually refers to the connection between your OBi and your VoIP Provider (in this case Google Voice).
After making sure you don't have the same Google Voice account setup on SP2, go to your SP1 settings and checking the username and password. On some GV accounts, we are required to type in the full Google Email Address (whatever@gmail.com) into the username blank. Then, re-type the current Google password. Submit, reboot, and report back here regarding the backing off status.
Voice Services -> SP1 Service -> AuthUserName
Voice Services -> SP1 Service -> AuthPassword
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