You can activate a new or used iPhone for use with a cellular service provider in a few steps. Here's how to activate any iPhone, or troubleshoot it.

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 ...

Changing physical SIM cards on your phone is always a fiddly business. First, you have to root for the little SIM tray tool ...

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

A SIM card, or subscriber identity module card, is essential component of any phone. It connects your device to a cellular network and stores vital information, including your phone number. Many ...