Will an iPhone with straight talk work in Montana?

I'm currently with straight talk and hate my phone. I want to buy an iPhone 5 or iPhone 4s from at&t and use it with straight talk. I want to know if this will work as well as will it work in Montana?

It should

That depends on your zip code. Go to the Straight Talk website and see if you can buy a Iphone in your zip code. You can also go to Straighttalksim and see if you can buy a sim card for your area code from Straight Talk.