This can be a pain in the ass when activating. ATT recently released this new system that will flag the device carded. So, I highly recommend not using for yourself or family member because it will send bill back to you after you activated it.
buy gift cards....then purchase what you need or pay bill.....not sure if it's everywhere now but at&t now key-in the last 4.....i mentioned that to say that they have changed their system somewhat so because of that i would purchase the at&t gift card and then use it at another at&t of your choosing.....