Q: I have an iPhone 3G which I will shortly be upgrading to an iPhone 4. I intend to sell the iPhone 3G and want to be certain that all personal information, call records, text messages, emails, internet history, songs, apps etc are deleted before I do so, with no possibility that the new owner can ever restore them.However I still want to retain all this information and data to transfer to my new iPhone 4.What is the best way to do this?
A: The iPhone includes a built-in option to securely erase everything on your device and return it to factory settings. You can find this in the Settings app under General, Reset.
When you’re ready to pack up your iPhone 3G for sale, simply go here and choose “Erase All Content and Settings” and after confirming that you actually want to do this, the iPhone will proceed to do a secure wipe of everything on your device, actually writing over the flash memory to prevent any chance of recovering data. The process will take a couple of hours, after which your iPhone will reboot back to the “Connect to iTunes” screen that appears on a brand new iPhone.
In terms of preserving your existing data before you do this, as long as you’ve synced your iPhone 3G to iTunes and have all of your existing media content and apps in your iTunes library, then you’re ready to go. iTunes automatically takes a backup of your iPhone each time you sync, and you can restore this backup to your iPhone 4 when you first connect it to your computer. You can check the status of your backups by going into your iTunes Preferences and selecting the Devices tab. You should see the name of your iPhone listed here with the date and time of the last backup.