Porting number from different metro areas

Hello,

I moved recently from New York to Atlanta. My current cell phone is not with AT&T and out of contract. I would like to keep my NY number at least in the short term. I was in Best Buy today and they told my I could not port my number. I was on a chat with an AT&T rep and they said I could. I'm more inclined to believe AT&T since it's their service. My question is, if I buy the phone from Best Buy, they're offering a better deal on the phone than AT&T right now, with a local number, would I be able to later port my NY number later on over the phone with AT&T customer service?

Thanks,

James