Hi Mark:
This is all stuff that is happening to your Google Voice account. I assume, from your post, that you did successfully set up your OBi with your GV-supplied phone number, and you can currently both make outbound calls, and receive inbound calls to the GV number. If so, then there isn't any action you need to take on your OBi device or web portal page.
The OBi is authenticated to your Google Voice account, and not to a particular phone number on that account. The OBi will use whichever GV phone number that is designated on your GV account as "primary".
Porting happens in stages. First, your ported-in number will start working as the caller ID for outbound calls. Then, usually around the 24-hour mark, inbound calls made to your ported-in number will get moved over to your new carrier's (GV's) inbound switch. Don't panic if this takes a bit longer (into the next day).
When you have an existing GV number, and you subsequently port in a second number, after that port is truly completed, then the ported-in number becomes primary. The first number, if it came from Google's pool, goes on "death row" for 90 days, to allow users time to let their contacts know about their new inbound number. During that 90-day period, you can optionally pay another $20 fee to keep the first number as a permanent number. IF you do that, then both numbers become permanent, and both will receive inbound calls and ring your OBi. The number you designate as "primary" will be used as caller ID for all outbound calls. You can flip the two numbers between primary and secondary mode at will, for free, as often as you wish, on your GV phone settings page.
If you don't want to keep the GV-supplied phone number then don't pay the second $20 fee, and just let it disappear on the 91st day.
Special case: if your first number was also a port-in, it would automatically be made permanent, with no need to pay another $20, since you already did that when you ported it in. This doesn't apply in your particular case, but I'm just noting this for other readers.