The first step, however, is to check the edges of your device for a small oval-shaped or rectangular cutout with a pinhole inside, as this is where the SIM tray is. Any object or implement with a ...
If you have an iPhone 3G, iPhone 3GS, iPhone 4, or iPhone 4S, the serial number is on the SIM tray. See our article on removing your iPhone's SIM card to learn how open the SIM card tray.