Great.
So, let's do this methodically. First, delete the OBi off of the OBiTALK dashboard,
before you reset it. Wait for the LEDs on the device to stop blinking while OBiTALK remotely resets it. The internet LED will just flicker and the power LED will be on steady.
Next, pick up the phone and key in ***8, then 1 to confirm restoring the OBi to factory defaults. Let the device churn for at least several minutes while you do the next steps:
Meanwhile log into your Google account on your computer, and go here:
https://myaccount.google.com/In the "Sign-in and security" section on the left, click the "Connected apps & sites" link. On the next page, click "MANAGE APPS". On the next page, look closely at the list. Click on anything that looks suspicious to expand it, and, if it looks like something you don't use anymore, delete it. Look for "Google Voice", with the little OBiTALK logo to the left of it. If you find it, delete it. If you don't find it, don't worry. This will clean out any corrupted or incorrect authentication link between OBiTALK and your Google account.
Now, go ahead and set up Google Voice on your OBi, while logged into the one and only Google account that you want to use with it. Leave the Google web page open in one browser tab, while you have OBiTALK open in another tab, and make absolutely sure that you associate your device with the correct Gmail address.