You are not understanding the basic operation of Google Voice, vs. the role that an OBiTALK device plays.
Google Voice is a service, just like Gmail or Calendar or Contacts or Docs. All Google services are accessed via a Google account (Gmail address). When you set up Google Voice
on the Google Voice website, you will first claim one of Google's free inbound phone numbers. This is mandatory. Then, you link various devices to that number, which act as forwarding destinations. Inbound calls to a Google Voice phone number can forward to any combination of:
- The Web client on Firefox or Google Chrome browsers.
- The Google Voice Android or iOS apps.
- Up to six 48-state US 10-digit telephone numbers.
- As many OBiTALK 200 series, 1000 series or 2000 series devices as you wish.
An OBiTALK device can act as a Google Voice VoIP forwarding destination. To do that, you authorize one of the Service Provider (SPx) configuration slots on the device to use the Google Voice service on your Google account.
The device is authorized to the account, not to the phone number. It doesn't matter if you subsequently add a second Google Voice number by porting in a number, or if you change the Google Voice number; it will simply work.
So, yes: first start by following the instructions to link your OBiTALK device SP to your Google Voice account. Now, it can make and receive calls using the free number you selected. If you are satisfied with the service, then initiate porting in your desired phone number. After the port completes, the ported in number becomes the primary number used for outbound calls. Inbound calls to either number will ring the same destinations. The original (free) GV number then goes into a pending-deletion state for 90 days. During that time, you can either pay another $20 to keep that number, too (and thus have two different inbound GV numbers), or you can ignore it, and it will automatically be released back into the pool at the 90 day mark.
Here's a link to the Google Voice help page on porting:
https://support.google.com/voice/answer/1065667Does that make sense now?