if took iphone 2 year contract one what will happen if didn't pay the bill?

Not paying your wireless carrier's bill would result in negative reports on your credit history, which could hurt your ability to obtain consumer credit in the future, not just for cell phone contracts, but for purchasing a home, car, or even getting a loan for a business you may own. It would not be a good idea to purchase a phone with a contract with the intent not to pay the carrier's bill.

They would send it to collections, and it would ruin your credit. It sounds like you may not understand how damaging a single negative entry on your credit report can be. This is simply something you don't want to happen. No super-cool new phone could be worth that! The carrier will go to great lengths to recover the money you owe them. A reactivation fee is a charge the carrier collects if your service is shut off and you later pay the past due amount and have the service reactivated.

Once you are in the contact, they can suspend service if you do not pay your bill, which would result in negative credit reports, and there could be a reactivation fee, and ultimately a termination fee of up to $400. If you are trying to get a phone without a contract, I suggest waiting to see if Apple eventually releases an unlocked iPhone 5 or you can purchase an iPhone 4 (GSM) or 4S unlocked from http://apple.com/store. The unlocked phones are more expensive, but they don't lock you into a contract or a specific carrier.