It's not from Google Voice. Since you setup 911 service, you set that up with some VoIP provider, no? I suspect that your OBi is using that provider for your outbound calls, and since you didn't put any money in that account you're getting that message.
Dial **1 to force the call to SP1 and dial your number. If it goes through, that's your GV provider.
If you get the message, dial **2 to force the call to SP2. If it goes through, that's your GV provider and the message you got with **1 tells you that your 911 provider is setup there.
Note that if you want more than the phone number displayed on incoming calls, GV won't do that. You'd have to forward your GV calls into another provider to get that information added, and then sent to your OBi.