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 ...

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 ...

You can check to see if your iPhone is unlocked from a carrier using any of a few different methods.

If you need to find out your iPhone's carrier without a SIM card installed, you can do so through the Settings app.

We independently review everything we recommend. When you buy through our links, we may earn a commission. Learn more› By Ryan Whitwam Most people rarely think about SIM cards, the tiny plastic ...