Verified answer

You actually can't buy it from the app store.

You Cant buy the iPhone separately.

The only way to buy it separately is on ebay. and it cost around 600-800 dollars for a unlocked iphone.

Plus when you buy it from the apple store, you need at&t service + mandatory 30$ a month for internet charges.

iPhone from at&t only uses at&t sim card.

Unlocked iPhones on ebay can you any exist in sim card service.

Hope this answers your Question. Vote me as Best answer.!

In the U.S only AT&T and T-Mobile use a phone network that conforms to the same standard as the IPhone.