How to Reset an iPhone SIM Factory
You can try to fix any issues you're having with your iPhone by resetting and returning the device to its original factory settings. A reset will completely erase your iPhone and SIM card. You will lose all contact information, photos, settings, notes and apps that you installed. Record any information you wish to save before you attempt a reset. Or, use iTunes to create a backup of the phone.
Press the "Home" button on your iPhone. Slide your finger across the "Slide to Unlock" bar. Your home page will load.
Tap the "Settings" icon.
Tap the "General" tab.
Tap "Reset" at the bottom of the page. A new page will open.
Tap "Erase All Content and Settings."