How much would my At&T monthly bill be if I get an iPhone 5?

My family and I just switched to AT&T, and my mom got an iphone 4s, and my sister has a basic phone. I have a basic phone for now but want a iphone 5, how much would our monthly bill be and how much would I have to pay for my phone? We're getting the 3GB data plan

There's no 3GB plan but there's a 4GB the actual phone will be 700$ the 4BG monthly bill will be $110.00 a mounth

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