Can someone give a good primer on how this number portability thing works?
Is it geographically restricted?

Basically you can take your number with you, if you are within the area code. If you change service providers and do not move you keep the number. This is REQUIRED from all cell phone providers. It is not an option for them to say they can not. The FCC has guidelines as to how long this should take and the entire rules about it.

I think that one of the reasons the phone companies are scared of GV is that number portability is no longer a problem.

I would guess that a lot of people stay with their cell phone company mainly because they don't want to have to go through the hassle of changing their phone number (even though we all know it's just a phone call and 7 - 10 day wait). With GV, you don't have to worry about changing numbers because all you have to do is tell GV that all calls coming ang going from whatever new number you have should now go through the GV number.

@I Love New Jersey:
Here, Let me Google that for you...

Number portability means when you switch providers, you get to keep the same phone number. In the early days, the providers would not let you take your number when you switched providers. Which, of course, sucked for consumers.

I don't really understand how this has anything to do with number portability at all. GV will still ring to your Iphone. You can still make web based calls where GV will ring your phone & then the target number, so the far end will see your GV number on Caller ID. None of this has anything to do with moving a number over to another carrier. All it is a) having GV use VoIP find me/ring me option when you receive a call & b) using GVs PBX or whatever system to mask your Caller ID to show your GV # when placing a call. Again, don't see how the term "number portability" comes to play in any of this just that users want more options when using today's telephony system.

AT&T and Apple just don't want to place nice with the competition. There's nothing more to it then that actually.

@I Love New Jersey: Yes, it is geographically restricted. Portability is defined as Local Number Porting. You cannot transfer a New Jersey number to a California landline provider. You can transfer a NJ number to a cell phone provider, regardless of the area, as long as the billing address you list with them (Initially, while porting the number) is within the same area that the number is porting from. Then, after it was ported, you can change your billing address. Porting land line to land line is kinda of restricted. Porting from landline to Cell or Voip is easier, and vice versa.

Loop holes. Got to love them.

@silver-bolt: Are you sure? I ported a number from one state to another and from one provider to another with nary an issue. It allowed me to keep the phone number I've had for close to a decade. And the billing address I used for the new provider in the new state was definitely outside the local area of the old number, unless you define "local area" as "a couple of states."

@lehrdude: 7 to 10 DAYS?!?! Up here north of the border it takes minutes... When I went from Bell to Rogers my number was ported before I left the store

@I Love New Jersey: It is if you're dealing with the traditional land-line carriers. Verizon couldn't even port my phone # a few miles down the street, same zip code, same street. Funny, Level3 had no problem doing so and they're based in Colorado.

@silver-bolt: With ATT, the loophole is even wider. All I was required to provide was an address. ANY address. Doesn't have to be your billing address. I made one up to keep my number. Not sure why I thought that would work better than just giving them my actual previous address, but it worked...

@MasterShazbot: Same for me in Philly - mobile phone number from ATT to Verizon. Just a few minutes.