How can I check if a used phone is stolen or locked before I buy it?

Check the IMEI, carrier-unlock status, account locks, and a live SIM before paying for a used phone.

Check the IMEI against a blacklist, confirm the phone is carrier-unlocked, and make the seller erase and set it up fresh in front of you before you pay. That sequence matters because a phone can look perfect yet still be tied to someone else’s Apple or Google account, financed through a carrier, or reported stolen later. A blacklist or activation lock can turn the device into an expensive brick, and a private sale may leave you with little recourse.1.

Find the IMEI. Dial *#06# or open Settings → About. Compare the number on-screen with the box and any receipt; mismatches are a warning.2.

Check the blacklist and carrier. Enter the IMEI at the CTIA Stolen Phone Checker, listed at stolenphonechecker.org, and use the original carrier’s own unlock or compatibility checker. A clean result is useful, but it is not a guarantee that an unpaid balance will never cause trouble.3.

Erase and activate it together. Have the seller sign out, disable Find My or the equivalent, fully erase the phone, and walk through setup on the spot. If Apple Activation Lock or Google Factory Reset Protection asks for the previous owner’s credentials, stop.4.

Test another carrier. Insert a working SIM or eSIM from a different carrier, place a call, send a message, and test mobile data. “Unlocked” should work in practice, not just in an ad.5.

Meet somewhere accountable. A carrier store can often confirm compatibility and account status. Get a written receipt naming the seller and listing the IMEI, model, price, and date.Pro tip: walk away if the seller refuses an erase-and-restore test or the price is far below the market.

Those are the two clearest red flags.