What is a SIM card used for? A SIM card, or a subscriber identity module/subscriber identification module, is a tiny memory card that contains unique information and is linked to a particular network ...

If you’ve bought an iPad with 4G/cellular capabilities (we discuss whether that’s a good idea in our 2015 iPad buying guide) or a new iPhone, you need to buy and install a SIM card. Here, we explain ...

Once you’ve activated your iPhone with your carrier, it should continue to work on the cellular network without any problems as long as you’re within range of a tower. Nevertheless, the vagaries of ...

Sareena was a senior editor for CNET covering the mobile beat, including device reviews. She is a seasoned multimedia journalist with more than a decade's worth of experience producing stories for ...