I guess it is to late to mention this, but here is my take on the "porting a number to GoogleVoice" process.
Sometimes it works, and it is desirable because it is free, but it also *may* be a hassle to make things work the way you want and many issues in the forums involve issues with the connection to GV. I am the first one to try to get free stuff (I have 4 GV numbers [shhhh] and a few free UK inbound ones, 2 Inums, 2 Sipgate numbers, a callcentric NYC number, a RingCentral one and 2 efax accounts). I am NOT unfamiliar with free :-) Still, I opted to pay for a number to reside with a Voip provider.
With that said, to the people who have had a residential landline number for decades or don't want to lose it, rather than try porting to Google, port it to someone like Voip.Ms
(who currently offers a free port) and pay the perhaps $12 to $18 a year and some charges for calling.
Yes, I love Google and its free, but it was pretty easy to just port to a provider other than Google and be done with it. (In reality, Google won't handle my area code anyway :-)
Still, the savings for most people is considerable enough that the slight charge for a paid provider might be worth it. $20-$40 a month compared to $20 a year, I'd be happy enough not to have to go buy a cellphone and try to port.
Just another view.