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.

You’ve just bought yourself an iPhone – welcome to the club! However, while you thought you’d just be able to pop your existing SIM card into your iPhone, you might be wrong. That’s dependant on not ...

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 ...

If you've just got your hands on a shiny new Sim card, congratulations. Switching your Sim (the chip that dictates your allowance) can unlock huge savings. Now comes the crucial step of activating it ...

Are you trying to switch phones or carriers? You might need to swap SIM cards for that, and we can understand how confusing this process can be if you haven’t done it before. Today we’ll show you ...

We independently review everything we recommend. When you buy through our links, we may earn a commission. Learn more› By Ryan Whitwam It's the final Prime Day of the year! See all of the (actually ...