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How to Check a Used Phone Before You Buy

Buying a used phone carries real risk — but almost all of it is preventable with a proper inspection. Whether you're buying in person on Facebook Marketplace or ordering a certified refurbished device online, there are specific things to verify before handing over money.

This guide gives you a complete, step-by-step checklist. Print it, bookmark it, or memorize it — your wallet will thank you.

The Pre-Purchase Checklist at a Glance

Step 1: Verify the IMEI Before Anything Else

The IMEI (International Mobile Equipment Identity) is the unique identifier tied to every phone. Checking it tells you:

• Whether the phone has been reported stolen or lost
• Whether it's blacklisted by a carrier (won't work on that network)
• Basic device info (model, manufacturer, carrier)

How to find the IMEI:

• Dial *#06# on the phone — it appears on screen instantly
• iPhone: Settings → General → About → IMEI
• Check the box or SIM tray (often printed there)

Where to check the IMEI:

• iPhone: devicecheck.apple.com — Apple's official tool, checks activation lock status too
• All phones (US): CTIA stolen phone checker — checks against all major US carrier blacklists
• IMEI.info — free international database check
• Swappa — has a built-in IMEI check tool

A blacklisted IMEI means the device is permanently blocked from most US carriers. It's essentially a brick for phone service — only usable on Wi-Fi. Walk away.

Step 2: Check for Activation Lock (iPhones) / Google FRP (Android)

This is the single most common scam in the used phone market. A device locked to a previous owner's account is worthless to you.

For iPhones — Activation Lock:

Go to icloud.com/find and enter the IMEI or serial number. If Activation Lock is ON, the previous owner's Apple ID is still linked. Don't buy it unless the seller can remove it in front of you.

Alternatively: Settings → General → About → Check if an Apple ID is linked under iCloud in Settings.

For Android — Google FRP (Factory Reset Protection):

After a factory reset, the phone will ask for the previous Google account during setup. If the seller can't provide it, the phone is locked. Ask the seller to factory reset the phone and walk through setup — verify FRP doesn't trigger.

Red flag: Any seller who says "I'll remove it later" or "send me the money and I'll unlock it remotely." This is a scam. The account must be removed before you pay.

Step 3: Check Battery Health

Battery degradation is the most common functional issue with used phones. A phone with 70% battery health may only last 4–5 hours — miserable for daily use.

iPhone Battery Health:

• Settings → Battery → Battery Health & Charging
• Look for the percentage under "Maximum Capacity"
• 80%+: Acceptable for purchase; Apple considers 80% the end of optimal life
• 85%+: Good
• 90%+: Excellent for a used device

Android Battery Health:

• Samsung: Dial *#0228# → Battery status → current capacity vs. design capacity
• Google Pixel: Settings → Battery → Battery health
• Third-party option: AccuBattery app (install, charge to 100%, it reads health)
• Many Android vendors hide this — ask the seller what their battery health reading shows

Refurbished phone note: Reputable certified refurbishers replace batteries below 80% health. If a certified refurbished listing doesn't mention battery health, ask — or buy from a seller who guarantees it.

Step 4: Inspect the Screen Carefully

Screens are the most expensive component to replace — and the hardest damage to hide. Inspect:

In person:

1. View from multiple angles under bright light — scratches show up in raking light
2. Display a pure white screen and a pure black screen — look for dead pixels, yellow patches, or dark spots
3. Run your finger across the surface — cracks show as resistance or catches
4. Check all four corners and edges where drops typically cause impact damage

OLED screens (most modern flagships): Watch for "burn-in" — permanent image retention from static elements (navigation bar is a common victim). Display a solid gray image — burn-in appears as faint ghost images.

Online purchases: Read grade descriptions carefully. "Grade A" should mean no visible scratches from 12 inches. "Grade B" may have marks. Ask for additional photos at angles.

Step 5: Test Every Physical Component

Work through this list systematically:

Cameras

• Open camera app, test front and rear
• Take a photo in daylight — check for autofocus speed, sharpness
• Test portrait/night mode if applicable
• Check for stuck pixels or smudges on the lens

Speakers and Microphone

• Play music or YouTube — listen for crackling, distortion, or rattling
• Record a voice memo and play it back — tests the primary microphone
• Make a test call — tests the earpiece speaker and call mic

Buttons

• Press power, volume up, volume down, and (if applicable) mute switch/fingerprint button
• Each should click cleanly with no mushy or sticky feedback

Biometrics

• Face ID (iPhone): Unlock test from multiple angles
• Face unlock (Android): Test in varying light
• Fingerprint sensor: Register a test print, attempt unlock
• In-display fingerprint (Samsung, Pixel): Test multiple finger positions

Charging and Connectivity

• Connect the charger — verify the device charges
• Test wireless charging if the model supports it
• Connect to Wi-Fi — test speed with a browser
• Test Bluetooth by pairing headphones

SIM Slot

• Verify the SIM tray opens and closes properly
• Insert your SIM and test calls/data

Step 6: Check the Physical Condition

Beyond the screen, examine:

• Back panel: Cracks, chips, or significant scratches
• Camera bump: Cracked lens covers, loose camera module
• Charging port: Debris, bent pins, loose connection
• Water damage indicator: On iPhones, the Liquid Contact Indicator (LCI) is inside the SIM tray slot. White/silver = no water damage. Red/pink = water exposure

Step 7: Run a Full Diagnostic (Optional but Smart)

For thorough in-person checks, use a diagnostic app:

• iPhone: Phone Diagnostics — tests all sensors, speakers, and display
• Android: Phone Doctor Plus or AIDA64 — comprehensive hardware test
• Samsung: Dial *#0*# — opens Samsung's built-in diagnostic menu (tests each component individually)

Red Flags: When to Walk Away

• Seller won't let you check IMEI
• Activation Lock / FRP is still on
• Price is dramatically below market (often signals stolen device)
• Seller wants payment via wire transfer, gift cards, or Zelle (no buyer protection)
• "It works fine, just needs [specific part] replaced" — verify this claim yourself
• No return policy on an online sale
• Photos are clearly stock images, not the actual device

Online Purchase Checklist

When you can't inspect in person, do this:

• Request IMEI and run your own check
• Ask for battery health screenshot
• Request angle photos of screen in bright light
• Confirm the device is factory reset (Activation Lock removed)
• Verify warranty and return policy in writing before paying
• Pay via method with buyer protection (PayPal Goods & Services, credit card)
• Never pay via gift cards, wire transfer, or crypto

FAQ

Q: How do I check if a used iPhone is stolen? Run the IMEI through devicecheck.apple.com (Apple's official tool). It will show if Activation Lock is on. Also check stolenphonechecker.org for carrier blacklist status. If either shows a problem — walk away.

Q: What's a good battery health percentage for a used phone? 85%+ is a solid used purchase. 80% is acceptable if the price reflects it. Below 80%, insist on a battery replacement discount or walk away — at 70%, you're looking at a phone that needs a $50–$100 battery replacement immediately.

Q: Can I check if a Samsung is stolen? Yes — run the IMEI through stolenphonechecker.org or Samsung's own IMEI checker at samsung.com. Also ask the seller to show you Samsung Account is not linked under Settings.

Q: What happens if I buy a blacklisted phone? A blacklisted phone won't connect to US carrier networks for calls or data. It can still use Wi-Fi. If this happens, you may have legal recourse if you bought through a marketplace with buyer protection (Amazon, PayPal, eBay) — file a claim immediately.

Related Guides:

• Best Places to Buy Used Phones Safely (2026)
• Certified Refurbished vs Used vs Pre-Owned: What's the Difference?
• Do Refurbished Phones Come with Warranty?
• Best Refurbished iPhones to Buy in 2026