Lance Whitney is a freelance technology writer and trainer and a former IT professional. He's written for Time, CNET, PCMag, and several other publications. He's the author of two tech books--one on ...

Will my Verizon iPhone 5S work on AT&T? That's a question asked by one Ask Maggie reader confused by the puzzling state of device interoperability. This week's column tackles the issue. Marguerite ...

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 ...

The SIM card in your iPhone is crucial to your making calls, but it's also small enough to lose, and easy enough to put in the wrong way. Here's how to successfully remove a SIM card, and put one back ...