Some owners of Apple's new iPhone 4S have been hit with SIM card error messages, even if they are connected to a CDMA carrier that does not use SIM cards. One reader ...

Use a SIM ejector tool or paperclip to gently remove the SIM tray. Take out the SIM card and inspect it for damage, such as ...

A dual-SIM setup lets you use one phone to make and receive calls and texts from two numbers. It's also super convenient and can save you serious cash when traveling. We show you how to use two SIMs ...

These two ways of connecting your phone to a cellular network are very different. We tell you about each and how you can switch from one to another. I started my career with CNET all the way back in ...