GearGuide 06 of 10
Buying a Used Phone: 10 Checks Before You Pay
A used phone can be a great deal, unless it’s stolen, locked to someone else’s account or quietly repaired with cheap parts. Ten checks, most of them free and fast, cover the big risks.
Buying a used phone from a stranger is mostly about avoiding three expensive problems: a phone that’s been reported lost or stolen, which can be blocked from cellular networks; a phone still tied to the previous owner’s account, which you may not be able to set up at all; and a phone with hidden repairs or a worn-out battery.
Do these checks in person, with the phone in your hands, before any money changes hands. Bring a charger and your SIM card, or make sure you can set up an eSIM, and give yourself 15 minutes.
1. Check the IMEI
Every phone has a unique identifier called an IMEI. Dial *#06# to display it, and check that it matches the number in the phone’s settings, and on the SIM tray or the box if there is one. Then look it up in a stolen-phone database. In the US, the wireless industry association CTIA runs a free Stolen Phone Checker that searches devices reported lost or stolen to participating carriers.
A clean result isn’t a guarantee. A flagged result is a dealbreaker.
2. Make sure the old account is gone
Phones have anti-theft locks tied to the owner’s account: Activation Lock on iPhone, which is part of Find My, and Factory Reset Protection on Android, which is tied to the Google account. If the seller doesn’t remove their account properly, the phone can ask for their password after a reset, and you’ll be stuck.
Ask the seller to sign out of their Apple Account or Google account and erase the phone in front of you. After the reset, it should start at the setup screen and let you finish setup without anyone else’s password. Never accept “I’ll remove it remotely later.”
3. Confirm it’s unlocked and paid off
A carrier-locked phone works with only one carrier until it’s unlocked. Ask whether it’s unlocked, and confirm where you can: on an iPhone, Settings > General > About shows a Carrier Lock line, and “No SIM restrictions” means it’s unlocked.
Also ask whether the phone is fully paid off. Phones bought on installment plans can be blocked by the carrier if the payments stop, even after the phone has been sold. Then test it with your own SIM or eSIM: make a call, and load a web page over cellular data, not Wi-Fi.
4. Look at battery health
On an iPhone, go to Settings > Battery > Battery Health (Battery Health & Charging on some models) to see the maximum capacity compared with when it was new. Apple generally considers a battery below about 80% of its original capacity to be worn. Android phones vary: some show battery health in settings, and some manufacturers offer diagnostics in their support apps.
A tired battery isn’t a dealbreaker, but a replacement costs money, so it belongs in the price.
5. Check for non-genuine parts
Repairs aren’t bad in themselves, but cheap replacement screens and batteries can mean worse brightness, touch problems or shorter battery life. On recent iPhones, Settings > General > About includes a Parts and Service History section when parts have been replaced, and it can flag parts that aren’t genuine Apple parts or couldn’t be verified.
On Android, look for physical clues: a screen that sits slightly unevenly in the frame, mismatched colors, missing screws or a fingerprint reader that doesn’t work.
6. Inspect the screen closely
Open a plain white image or a blank web page at full brightness and look for dead pixels, discolored patches or a faint ghost image that doesn’t go away. That’s burn-in, which is common on older OLED screens.
Then open an app where you can draw, or drag an icon around, and slowly run your finger across every part of the screen to find dead touch spots. Finally, check for scratches with the screen off, under a light.
7. Test every part that matters
Run through it quickly:
- front and rear cameras, every lens, and the flashlight;
- Face ID or the fingerprint reader;
- speakers (play a video) and microphones (record a voice memo, then make a call);
- buttons, vibration and the charging port, using your own cable;
- Wi-Fi and Bluetooth;
- wireless charging, if the phone supports it.
Five minutes here prevents most “it worked when I sold it” arguments.
8. Look for signs of water damage
Water damage can cause problems weeks later. On iPhones with a SIM tray, a liquid contact indicator inside the SIM slot turns red after contact with liquid; use a flashlight to look. Other signs on any phone include fog inside the camera lenses, corrosion in the charging port, a muffled speaker and patchy areas on the screen.
9. Confirm the model, storage and update support
Check the settings for the model name, storage capacity and software version, and make sure they match the listing. A different regional version may lack network bands your carrier uses. Then check how long the phone will keep getting software updates: an old phone that no longer receives security updates is riskier to use, and worth less.
One more detail for US buyers: iPhone models sold in the US since the iPhone 14 have no SIM tray and work with eSIM only. Major US carriers support eSIM, but confirm you can move your line before you buy.
10. Pay safely and get it in writing
Meet in a busy public place in daylight; many police departments offer safe exchange zones in their parking lots or lobbies. Don’t pay until you’ve done the checks above. Cash is simple in person. If you pay digitally, prefer a method with buyer protection, and never send money in advance for a phone you haven’t seen.
Finally, get a short written receipt with the date, the price, the model, the IMEI and the seller’s name.
Before you meet: ask by message
A few questions before you travel can save a wasted trip:
- How long have you had the phone, and why are you selling it?
- Has it ever been repaired? Where, and which parts?
- Is it unlocked and fully paid off?
- What does the battery health show?
- Can you send me the IMEI? (Check it before you go.)
- Will you sign out of your account and reset the phone in front of me?
Walk away if the seller won’t share the IMEI, wants a deposit before you meet, can’t meet in person, or is asking far less than the same model sells for elsewhere.
The bottom line
The two checks you can’t skip are the IMEI and the account lock, because they decide whether the phone is usable at all. Everything else decides the price.
Your 10-point checklist
- The IMEI matches and isn’t flagged as lost or stolen.
- The seller’s account is removed and the phone is reset.
- It’s unlocked, or locked to your carrier, and fully paid off.
- Battery health is checked, ideally 80% or more.
- Parts history shows no surprises.
- The screen has no dead pixels, burn-in or dead touch areas.
- Cameras, face or fingerprint unlock, speakers, mics and ports work.
- There are no signs of water damage.
- Model, storage and update support are confirmed.
- You paid safely and got a receipt that lists the IMEI.
Take a screenshot, or print the page: the checklist prints without the menus.