Even with the worst phone you can buy from most carriers, these would still apply: "your entire address book, your chat history, all your personal photos"
Just factory reset your phone before going through, and restore it after you've completed your TSA adventure. Though, do NOT brag about your tactic to them or they will likely try to force you to restore it on the spot.
I've showed my Nokia 5110 with prepaid couple of times when checked at border. Usually the first question they come up with is: "Is this really the primary phone you're using." Just smile and say yes. I don't have any other phones with me. That's all I need to contact someone to pick me up.
If you need new identity & SIM card, you can just pick one using cash from SIM card vending machine. Someone said that getting anonymous phone is hard, lol.
