Hi Folks here's very simple solution to this problem. As just like you all I've spent 3 days to get this resolved and finally today after being on phone with an Apple representative (Charles) for 3:40 hours we got it resolved.We had to call At&T several times but none the less we got it resolved.
Here's what you'd do its Guaranteed to work.
Call At&T and explain them that because your account is considered a cross market account its not letting you upgrade your line at Apple Store or Apple.com so you need your number changed to match Area code that matches your Billing Zip code's area code. (My original number was from Illinois 630 area code and i had to change it to 402 Omaha area code to match my Zip code) Keep in mind you don't need to change your phone # permanently. its just for a brief period till apple.com or apple store let you place an order with your new phone # and than you can switch your number back to whatever it was.(Ones you change your number, you have 59 days to reclaim the same number,after that its available for anybody to grab it.) the whole process takes 20 to 30 minutes maximum.
At&T will charge you $36 to change your number so be nice and request to have this $36 fee waived.i got mine waived.
Please guys try this out and I'm sure it'll definitely work for you. Let me know if you have any question on this matter.
1.Call AT&T
2.Change Your number to match with your billing Zip code.
3.Place and order.
4.Switch your number back to what it was.
5. Let me know if this works for you guys or not.
Thank You all.