Turn the phone on. If you see an "iPhone Locked to Owner" screen, it is likely stolen. The seller must remove their Apple ID and turn off "Find My" in front of you.

These are the absolute deal-breakers. If a phone fails any of these, .

Go to Settings > General > About . Look for "Carrier Lock." It should say "No SIM restrictions" . If it shows a specific carrier, it is locked to that network. 2. Hardware & Physical Inspection If you want to buy a preowned iPhone - Apple Support

When buying a used iPhone, your priority is verifying that the device isn't stolen or "bricked" before moving on to hardware health. 1. Critical Software & Security Checks

Dial *#06# to get the IMEI number. Check this number on a reliable site like the Stolen Phone Checker (US) or Swappa to ensure it hasn't been reported lost or stolen.