That is simply impossible, if you have correctly set up your OBi. Google Voice cannot/will not not ring the Chat destination unless the box is check-marked. You may be looking at a different account on the GV website, than is configured on your OBi.
The fool-proof way to resolve this is:
Open a web browser. Log onto the correct GV account, to the Phones tab of Settings, per my last post. Confirm that you see the exact two words "Your number" on the left side of the page, not "Access number" or "Get a Voice number", and below that, is indeed, the Google Voice number in question, and not some other GV number you may have acquired. If it is not the correct account, then you'll need to figure out the login credentials for whatever other GV account you might have created, and log in to that account.
Leave that page open and logged into your correct GV account. Press Ctrl-T to open a new browser tab. Log into your OBiTALK portal page. Delete the OBi off of your account entirely. Wait a couple of minutes and it will send a factory reset command to your OBi. For good measure, I would then manually factory reset it again, just to make sure it is completely clean.
Add the OBi back to the OBiTALK portal, using the **5 method. Now, configure Google Voice on one of the Service provider slots. It will pop up a browser window, logged into that same Google account, and ask for your permission for OBiTALK to access the appropriate services on your GV account. Then, it will spin its wheels for a few minutes while it exchanges secure access tokens via OAUTH 2.0. After it is done, it is in fact set up with that GV account and nothing else.
Call your GV number. It will only ring that OBi if Chat is check-marked. After you have this tested and working correctly, you can then add your SIP account to another SP on the device.