Thanks for the additional information.
This reminds me of the quote attributed to Nobel laureate physicist
Enrico Fermi:"Before I came here I was confused about this subject. Having listened to your lecture I am still confused. But on a higher level."
There could be several different things going on at once, all combined to create a mess. Let's try just a few steps at a time. The fact that you moved your GV number around makes me suspicious:
On your Android phone, log out of the mobile Google Voice app, and delete it entirely off of the phone (don't just delete the shortcut, but go to Settings -->Apps, and force-close the app, then delete the app's cache, data, and the app itself). Power-cycle your phone.
Log into your Google Voice account from a laptop or desktop computer, not from your phone. Go here:
https://www.google.com/voice#phonesTell me that it does, in fact, say "Your number" on the left side of the web page. Then, hover your mouse cursor on the avatar at the upper right corner of the page (either a generic blue head and shoulders, or your photo if you uploaded one). It should display your user name (your Gmail address). Look carefully to be sure it's the one you want to use, since it is all too easy to be logged into multiple Google accounts in the same browser. If it is the wrong address, log out and then log back in with the right address.
Log into your OBiTALK portal web page. Click on the [Expand] link if necessary to display SP1 through SP4. Click on the SP that is assigned to your GV account. Click "Accept" in the pop-up box. Now, look at the Google Voice "Active Google Username". Confirm that it is an exact match to the user name shown on the GV Settings webpage I linked above. If it isn't, then click the link to replace the Google account.
If this is all correct so far, then call your Google Voice phone number from some unrelated phone number. Confirm that your OBi-attached telephone rings, and that it displays the caller ID number of the calling party. Now, hang up and do the reverse: from the OBi-attached phone, call the other phone number. That phone should display your GV telephone number as the caller ID. Did this work as I described?