Address change on AT&T?

I've seen people talking about changing their address for orders directly thru Apple but what about AT&T? Any problems doing that after the order is already in?

My billing address is a PO Box at the UPS Store and while I can get it there, I'd rather have it delivered to my house so there is no delay.

 

My billing address for my credit/debit card is at the PO box though some. Ant change that or then payment won't go through. I'll have to call AT&T tomorrow and see if I can change the address.