A guide to SIM cards, the small chips that connect your phone to a cellular network

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.

7 ways to troubleshoot if your phone's SIM card isn't working

If you can't make a call or if you see an error message that your phone's SIM card is not working, there are several ways to ...