Apple iPhone

Ok, heres the deal. I am an indirect dealer who would like an iphone. The only thing is that i don't really want to pay for the iphone plan. I get great dealer discounts through at&t but unfortunately they do not apply for an iphone. My question is this... If i get the iphone unlocked, can i still use it on a normal at&t dealer plan and not an iphone plan? I know i would be sacrificing visual voice mail but that would be it, right? In theory anyways.