Q: What’s my SIM card serial number for? A: Your SIM serial number (SSN), sometimes called the ICC-ID (Integrated Circuit Card ID), is for international identification. The SSN typically has 19 digits ...

For most models of iPhone, figuring out how to find the serial number is as simple as opening the Settings app. For older models, it's on the SIM tray or the back of the phone. If you can't turn on ...