If I Put My Samsung SIM Card in My iPhone, Will It Work?by Robert Schrader
You can Insert a SIM card from a Samsung phone into an Apple iPhone to use the device with your existing service account. If you currently use AT&T with your Samsung phone, inserting the SIM card into any iPhone generates services. If you use the Samsung phone with a different carrier, on the other hand, its SIM card only works in unlocked, or "jailbroken," iPhones.
Hold down the "Home" and "Lock" buttons at the same time to power the iPhone off. Place the end of a paper clip into the hole next to the SIM card tray, located on top of iPhone 3G and older models, and on the right side of the iPhone 4.
Pop out the existing SIM card -- if there is one -- then place the Samsung SIM card into the SIM tray, face down. If you use an iPhone 4, only a small "microSIM" works in the device, so if your Samsung phone uses a standard-sized SIM, it won't work.
Replace the SIM tray and power the iPhone back on. If a network name appears in the upper left corner of the screen, you can use the iPhone with the Samsung SIM card.
- If your iPhone isn't already jailbroken -- if you insert the Samsung SIM card and it doesn't work, the iPhone is still locked -- don't attempt to unlock the phone itself, which voids your Apple warranty.