You need to be 18 to use the internet access i think.
Most Schools issue IDs these days.
In this video you have to be 18 to activate and do a credit check. I dont think they will let you activate in your name if you have no credit w/o a deposit.
http://www.apple.com/iphone/usingiphone/activation.html
i called the att store and they said you need to be 18 to purchace it