Find the IMEI on the iPhone by dialing *#06#, checking Settings > General > About, or looking on the SIM tray, box, or back of the device
Go to Apple’s Check Coverage page and enter the IMEI
Use a trusted IMEI checker website to verify activation status, warranty, and carrier lock
Contact your carrier and provide the IMEI to check if the phone is locked, blacklisted, or reported lost
Compare the IMEI on the device with the IMEI in Settings and on the box to confirm it matches
Check the IMEI against a blacklist database to see if the phone has been reported stolen or blocked
Verify the iPhone model and region using the IMEI through an IMEI lookup tool
Confirm the device is not iCloud Activation Locked by asking the seller to erase it and remove it from their Apple ID before purchase