Can I sign up for an at&t contract if i don't have any credit?

I'm 23 and have very little credit. I purchased two new cars since i was 18 and was always a cosigner since mom had to put it in her name due to me working odd jobs through college. Besides that, no real credit.

I want to buy the new iphone 5, but am worried if i stand there all night, I might be denied. Can they do that? I currently make $2500/month as a sub teacher. I have 10k in savings. Worst case scenerio, will they just make me put a big down payment? Would they deny me?

If anything, they will make you pay a down payment.

They'll arrange a down-payment for you, no worries.