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 ...

Seeing “No SIM” or “Invalid SIM” on iPhone? Check your SIM card, restart, or update your carrier settings. Simple fixes often ...