Many sites claim they will check the IMEI for free, then tell you the phone is "Clean" but ask for $50 to "activate" the report. This is a lie. Legitimate reports cost $1–$3 max.

In the bustling secondary market for smartphones, iPhones hold their value better than almost any other device. But this popularity comes with a dark side: a flood of stolen, blacklisted, or iCloud-locked devices.

Here is everything you need to know before you hit that "Check" button. Every iPhone has a unique 15-digit code called the IMEI (International Mobile Equipment Identity). Think of it as a social security number for your phone. It is etched onto the SIM tray, printed on the back of older models, and accessible by dialing *#06# on the dialer.

If a seller refuses to give you the IMEI before you hand over cash, walk away. Legitimate sellers understand the concern and will happily provide the number.