First unlock your iPhone. Get a non smartphone. Put your AT&T sim into it. Call customer service' with that non smartphone. say you lost iPhone. You wAnt to use your old phone and remove the data plan from it. They ask you the imei of your new phone which you are using to call them. Say you can't get the battery out while stillon the phone with him/ her because it will disconnect the call. If they ask you to punch in some codes from your phone while the call is still active say # or * key don't work on your phone. Now AT&T can't register you with a particular phone. This means when you insert your sim in any smartphone even iPhone they wont track or may be don't know. I did this in 2009. Dont know what they are up to now. Using droid now, love it. Miss the app store though.