SIM cards have been an integral yet forgettable aspect of owning a smartphone over the past few decades. For most users, the SIM card defines the basic commercial relationship they have with their ...

A SIM card, or subscriber identity module, is a small card in your cellphone that lets you place phone calls, send text messages, and more.

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.

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 ...