I don't know why you can call the ported cell phone number from "the current GV in a browser", whatever that means, but you cannot call that number from "the current GV in the Obihai". Your terminology is so borked up that it makes no sense.
Google Voice is an inbound telephone call forwarding service. It uses regular telephone connections for all calls, not VoIP. If you have an inbound Google Voice number, you then configure that number to forward inbound calls to a) up to six US-based, 10-digit telephone numbers and b) to "Google Chat". OBi (not "Obitalk" or "Obihai") devices act as Google Chat clients.
Google Hangouts is the VoIP service for Google Voice, and it works independently of Google Voice/Chat.
When you make an outbound call on a laptop or desktop computer, you are either initiating that call from Google Voice or from Hangouts. If you click the "new call" button on your Google Voice web page, then you are telling Google Voice to call you on a 10-digit forwarding phone number. When you answer that number, Google Voice will then call your desired party and bridge the two calls together. This is not a VoIP call.
When you make an outbound call, either from your Gmail page, or from the direct Hangouts page, you are using Hangouts, not Google Voice.
When you make or answer a phone call on an OBi that is connected to a Google account, the OBi is using the old, Google Chat XMPP protocol to make or receive the call via VoIP.
I have no idea what is going on with your ported number, but it sounds like it is messed up. I can't help you with that, and I would strongly advise against porting that number again, to Google Voice, unless you can get it fully working.
Try adding and verifying some other mobile or land line number as a linked forwarding number on your Google Voice account, and see what the behavior is with that number. I don't want to waste time trying to get your ported number working, as I have no ability to troubleshoot it.