To check used phone before buying, meet in person, in good light, with the phone switched on. Match the IMEI in Settings → About phone to the box and the listing, ask the carrier you plan to use whether that IMEI can be activated, and make sure the seller has removed their Google account (and Samsung account on a Galaxy). Then test the screen, buttons, cameras, mic, speakers, charging and battery.
If the seller won’t show you the IMEI or won’t sign out of their accounts in front of you, walk away. A phone still linked to someone else’s Google account can be unusable after a reset.
A used Android phone can be a great deal. It can also be stolen, still owed on a carrier plan, locked to a network you don’t use, or quietly broken. Most of those problems show up in a few minutes if you know where to look. This checklist works for Samsung Galaxy phones and for Pixel and other Android phones. Menu names can differ slightly by model and Android version.
Before you meet: questions to ask the seller
- Which carrier was it used on, and is it carrier-unlocked? A locked phone may only work with the carrier that sold it.
- Is it fully paid off? Carriers set their own unlock rules, and many won’t unlock a phone that still has a balance on it.
- Can you send the IMEI before we meet? An honest seller has no reason to refuse. You can ask a carrier about it before you travel.
- Do you have the box and receipt? Samsung notes the original box may list the full IMEI and serial number. A receipt is the simplest proof of ownership.
- Why are you selling it? Not a test, but a vague or changing story is worth noticing.
How to check used phone before buying: the IMEI first
Every phone has an IMEI, a unique number that carriers use to identify it. Samsung lists several places to find it on a Galaxy:
- Settings → About phone (or About tablet).
- Dial
*#06#. Samsung says this only works when supported by your carrier. - Printed in small text on the back of the phone near the bottom, on models that have it there.
- On the original box, and on the seller’s receipt or carrier account.
The IMEI in Settings should match the box and the number the seller sent you. If it doesn’t, treat that as a serious warning sign. Swapped boxes are a common way to make a phone look legitimate.
Check carrier lock and blocked status the official way
Use the IMEI only with official routes. Don’t type it into random “IMEI unlock” sites or apps that ask for money or personal details.
- Ask the carrier you plan to use. US carriers ask for the IMEI when you bring your own phone, and they can tell you whether it can be activated on their network.
- Ask the original carrier about unlock status. Unlocking is handled by the carrier that locked the phone, so the seller may need to request it from their account.
- Check whether it has been reported lost or stolen. CTIA, the US wireless industry association, runs a free Stolen Phone Checker that looks up an IMEI.
If the IMEI comes back as reported lost or stolen, don’t buy the phone, even at a big discount. A blocked phone may never work on a US network, and you won’t get your money back from a stranger.
Make sure the seller’s accounts are gone
Android has a feature called Factory Reset Protection. Google’s Android Help explains that after a factory reset, the phone asks for the screen lock or a Google Account that was on it, and if you can’t give that information during setup, “you won’t be able to use the device at all.” It’s there to stop thieves, but it also traps buyers who get a phone still tied to the seller.
- Ask the seller to open Settings and remove their Google account. Look for an Accounts section; the exact name varies by phone.
- On a Galaxy, ask them to sign out of their Samsung account too.
- Ask them to factory reset the phone in front of you. Google notes that a factory reset erases all data on the phone, so make sure they’ve backed up first.
- When the phone restarts, go through the first setup screens yourself. If it asks you to verify a previous Google account or screen lock, stop. The seller hasn’t removed it.
Never accept a phone stuck on a “verify your account” screen with a promise that the seller will unlock it later. There’s no legitimate way for you to get past it without the owner’s details.
Test the screen, buttons and cameras
- Screen: open our dead pixel test in the phone’s browser and go full screen. Step through the solid colors and look for dead or stuck pixels, bright patches, tinting and burn-in (faint ghost images on white or gray).
- Touch: drag an app icon slowly around every edge and corner. It should follow your finger without jumping.
- Buttons: press power, volume up and volume down. Each should click and respond.
- Cameras: take a photo and a short video with each rear camera and the front camera. Switch zoom levels and check that focus works.
- Biometrics: add a test fingerprint or face, check it unlocks the phone, then delete it.
- Flashlight and vibration: turn on the flashlight from the Quick panel and set the phone to vibrate.
- Body: look for cracks, a screen or back panel that’s lifting at the edges (which can mean a swollen battery), and damage in the charging port and SIM tray.
Test calls, the mic and the speakers
If you can, put your own SIM card in and make a call. Check that you can hear clearly through the earpiece and that the other person can hear you. Then use our mic test to make sure the microphone picks up your voice cleanly, and our speaker test to play tones through the left and right speakers at high volume. Listen for crackling, buzzing or one side that’s much quieter.
While you’re at it, connect to Wi-Fi (a phone hotspot works), pair a Bluetooth device if you have one, and load a web page on mobile data.
Run Samsung’s built-in diagnostics on a Galaxy
Galaxy phones have built-in tests that cover a lot of this checklist. Samsung’s support page gives two routes:
- Open Settings → Device care → Diagnostics, then tap Phone diagnostics.
- Or open the Samsung Members app, tap Diagnostics (on the Discover or Support tab), then Phone diagnostics.
- Tap Test all at the bottom, or tap single tests such as touch screen, battery status, speaker, mic and SIM card. Follow the on-screen prompts.
Samsung notes that Device care diagnostics need Android 12 or later, and the tests available vary by model. On a Pixel or another brand, check the maker’s own diagnostics or battery options in Settings.
Check the battery, charging and software
- Charging: plug in with your own cable and charger. The phone should show it’s charging within a few seconds, and the cable shouldn’t feel loose in the port.
- Battery: run the battery status test above on a Galaxy. Also watch the percentage while you test the cameras and screen. A level that drops fast or a phone that gets hot during light use is a bad sign.
- Software: check Settings → About phone for the model and Android version, then check for a software update. A phone that no longer gets updates is worth less.
- Work or school phones: if you see a message that the device is managed by an organization, it may belong to a company. Ask for proof it was released before you pay.
Pay safely and keep a record
The FTC’s advice for buying from online marketplaces applies to used phones too:
- Pay with a method that has protections, like a credit card. The FTC warns against wire transfers, gift cards and cryptocurrency, because once that money is gone you generally can’t get it back.
- Check the seller’s ratings and read comments from recent buyers.
- Get answers to your questions in writing and keep copies of your messages.
- Meet somewhere busy and public, during the day, and bring someone with you if you can.
If something doesn’t check out
- IMEI doesn’t match, or it’s reported lost or stolen: walk away.
- Seller won’t remove their account or reset the phone: walk away.
- A diagnostic test fails or the battery is weak: negotiate the price down or skip it. Repairs can cost more than the discount.
- You already paid and the phone turns out to be blocked: contact the seller, then the marketplace, then your card issuer to dispute the charge. The FTC says to report dishonest sellers at ReportFraud.ftc.gov and to your state attorney general.
Once the phone is yours, follow our guide to setting up a new Android phone. If anything strange was left behind, our guide to checking if your phone is hacked covers the warning signs. More guides live in the Android section.
Related guide: Lost Your Phone? How to Find It on Android, Samsung Galaxy or iPhone.
FAQ
How do I know if a used phone is stolen?
Get the IMEI from Settings → About phone and make sure it matches the box. Then ask the carrier you plan to use whether it can be activated, or look it up in CTIA’s Stolen Phone Checker. Walk away if the seller won’t share the IMEI.
Can I use a phone that’s still linked to the seller’s Google account?
Not reliably. Google says that after a factory reset, a protected phone asks for a Google Account that was on it, and without that you won’t be able to use it at all. Have the seller remove the account and reset the phone in front of you.
How can I tell if a used Android phone is carrier-unlocked?
Ask the seller which carrier it came from, then ask the carrier you plan to use to check the IMEI. Unlocking is handled by the original carrier, and many require the phone to be paid off first.
How do I check battery health on a used Samsung phone?
Open Settings → Device care → Diagnostics → Phone diagnostics, or the Samsung Members app, and run the battery status test. Available tests vary by model.
What’s the safest way to pay for a used phone?
Use a payment method with protections, such as a credit card. The FTC warns against wire transfers, gift cards and cryptocurrency for marketplace purchases.
Sources
- Find your Samsung phone or tablet’s IMEI, model, or serial number (Samsung US)
- Check your Samsung Galaxy device status and run diagnostics (Samsung US)
- Help prevent others from using your device without permission (Android Help)
- Reset your Android device to factory settings (Android Help)
- Buying From an Online Marketplace (FTC Consumer Advice)
