Buying a used unlocked phone can save hundreds of dollars, but it comes with risks. Scammers sell stolen, blacklisted, or damaged phones to unsuspecting buyers. This comprehensive guide will show you exactly how to verify a used phone is legitimate before purchasing.
Step 1: Check the IMEI Number
The IMEI (International Mobile Equipment Identity) is your phone's unique 15-digit identifier. It's the most important piece of information for verifying a used phone.
How to Find the IMEI:
- Dial *#06# on the phone
- iPhone: Settings > General > About > IMEI
- Android: Settings > About Phone > Status > IMEI
- Printed on the original box
- Engraved on the SIM card tray (some models)
What to Check:
- IMEI should match between phone settings, dialer, and box
- If IMEI doesn't display when you dial *#06#, the phone may be blacklisted or tampered with
- Write down the full 15-digit number before moving forward
Step 2: Verify the Phone Isn't Stolen or Blacklisted
Use free online IMEI checkers to verify the phone's status:
Recommended Free IMEI Checkers:
1. CTIA's Stolen Phone Checker: (StolenPhoneChecker.org)
- Checks against major US carrier blacklists
- Free and reliable
- Covers AT&T, T-Mobile, Verizon, Sprint databases
2. Swappa's ESN/IMEI Checker:
- Verifies if phone can be activated
- Checks blacklist status
- Shows iCloud lock status for iPhones
3. IMEI.info:
- Provides detailed phone information
- Shows blacklist status
- Verifies warranty status
Red Flags:
- "Blacklisted" or "Reported Lost/Stolen" status
- "Unable to activate" message
- Conflicting information between checkers
- "Blocked" on any carrier network
A blacklisted phone cannot be activated on most US carriers and has significantly reduced resale value. Never buy a blacklisted phone unless you plan to use it internationally only (and even then, be cautious).
Step 3: Check for iCloud Activation Lock (iPhone)
Activation Lock is Apple's anti-theft feature. A locked iPhone is worthless unless you have the previous owner's Apple ID credentials.
How to Check Before Buying:
- Have seller sign out of iCloud in front of you
- Go to Settings > [their name] > Sign Out
- After they sign out, reset the phone: Settings > General > Transfer or Reset iPhone > Erase All Content and Settings
- During setup, you should NOT see "iPhone is locked to owner"
If buying online/remotely:
- Ask seller to provide video of them signing out of iCloud
- Use Apple's Activation Lock checker (appleid.apple.com/activationlock)
- Meet in person whenever possible for used iPhones
Warning Signs:
- Seller refuses to sign out of iCloud
- Phone asks for previous owner's Apple ID after reset
- Seller says they'll "remove it later"
- Seller doesn't know the iCloud password
Step 4: Verify Google Account Lock (Android)
Android has Factory Reset Protection (FRP) that requires the previous owner's Google account after a factory reset.
How to Check:
- Have seller perform a factory reset in your presence
- Go through initial setup
- You should NOT be prompted for the previous owner's Google account
- If prompted, the phone is still locked to their Google account
How to Bypass (Legitimate):
- Seller must remove their Google account BEFORE factory reset
- Settings > Accounts > Google > Remove Account
- Then factory reset will not trigger FRP
Step 5: Physical Inspection
Examine the phone thoroughly for damage or signs of fraud:
Exterior Inspection:
- Look for cracks, deep scratches, or dents
- Check for water damage indicators (usually in SIM tray or charging port)
- Verify all buttons click properly
- Ensure charging port isn't damaged or loose
- Check camera lenses for cracks or scratches
- Look for signs of previous repair (misaligned panels, glue residue)
Screen Check:
- Display pure white screen (look for dead pixels)
- Display pure black screen (check for burn-in on OLED)
- Test touch response in all areas
- Check for screen lift or separation
- Verify no discoloration or yellow spots
Water Damage:
- iPhone: Check Liquid Contact Indicator in SIM tray (should be white, not red/pink)
- Android: LCI varies by model, check manufacturer specs
- Look for corrosion in charging port or headphone jack
- Check for moisture under camera lens
Step 6: Functional Testing
Test all phone features before completing purchase:
Cellular Testing:
- Insert your SIM card and verify it connects to network
- Make a test phone call
- Send and receive text messages (SMS and MMS)
- Test mobile data connection
- Try WiFi calling if your carrier supports it
Camera Testing:
- Test all camera lenses (main, ultra-wide, telephoto)
- Take photos in various lighting conditions
- Record video with sound
- Test front-facing camera
- Check flash functionality
Sensor Testing:
- Face ID/Face Unlock
- Fingerprint sensor
- Accelerometer (rotate screen)
- GPS (open maps)
- Proximity sensor (make a call, cover top of phone)
- Ambient light sensor (screen brightness adjustment)
Connectivity:
- WiFi connection and speed
- Bluetooth pairing with a device
- NFC (if applicable)
- USB data transfer
Audio:
- Speaker volume and clarity (play music)
- Microphone (record voice memo)
- Earpiece (make phone call)
- Headphone jack (if applicable)
Battery:
- iPhone: Settings > Battery > Battery Health (should be 80%+ for good condition)
- Android: Use AccuBattery app or check in Settings > Battery
- Battery health under 80% means replacement needed soon
Step 7: Verify Carrier Unlock Status
Just because a seller says it's "unlocked" doesn't make it true.
How to Verify:
- Insert SIM card from a different carrier than phone's original carrier
- If phone connects and makes calls, it's unlocked
- iPhone: Settings > General > About - if "Carrier Lock" says "No SIM restrictions," it's unlocked
- Android: Try different carrier SIM or check with seller's carrier
Step 8: Check Warranty Status
iPhone:
- Go to checkcoverage.apple.com
- Enter IMEI or serial number
- Shows if Apple warranty or AppleCare+ is active
- Displays purchase date and warranty expiration
Android:
- Samsung: samsung.com/us/support/warranty
- Google: support.google.com/store
- Most manufacturers have warranty checker on their support site
Where to Buy Used Phones Safely
Recommended Marketplaces:
1. Swappa:
- Every phone's IMEI verified before listing
- No blacklisted or iCloud locked phones allowed
- Seller ratings and buyer protection
- Reasonable fees
2. Back Market:
- Certified refurbished phones
- 1-year warranty included
- 30-day return policy
- Professionally tested and graded
3. Amazon Renewed:
- Amazon's refurbished program
- 90-day warranty
- Easy returns
- Professionally inspected
4. Manufacturer Certified Refurbished:
- Apple, Samsung, Google sell refurbished directly
- Often include warranty
- Thoroughly tested and repaired
- More expensive but safest option
Risky Platforms:
- Craigslist: No buyer protection, common scams
- OfferUp/LetGo: Less verification than specialized platforms
- Facebook Marketplace: Mixed results, meet in public
Red Flags to Avoid
Walk away if you encounter any of these:
- Seller refuses to provide IMEI before meeting
- Won't meet in public place or wants to ship before you pay
- Price too good to be true (50%+ below market value)
- Seller can't or won't sign out of iCloud/Google account
- Phone feels different than genuine model (might be fake)
- Original packaging/accessories seem suspicious
- Seller pressures you to buy immediately
- No receipt or proof of purchase
- Seller claims phone is "for parts" but lists as working
- Multiple phones for sale (might be selling stolen devices)
Safe Transaction Practices
- Meet in public: Police stations often have "safe exchange zones" for online sales
- Bring a friend: Extra person for safety and second opinion
- Cash or secure payment: Avoid wire transfers or apps with no buyer protection
- PayPal Goods & Services: Offers buyer protection (never use Friends & Family)
- Get a receipt: Written receipt with IMEI, date, price, seller signature
- Test everything first: Don't complete transaction until fully tested
- Trust your instincts: If something feels off, walk away
Price Guide for Used Phones
Used phone prices typically depreciate:
- 1 year old: 60-70% of original price
- 2 years old: 40-50% of original price
- 3 years old: 25-35% of original price
- 4+ years old: 15-25% of original price
iPhones retain value better than Android devices. Flagship Androids depreciate faster.
What to Do If You've Been Scammed
If you unknowingly bought a problematic phone:
- Contact seller immediately and request refund
- If purchased with PayPal/credit card, file dispute
- Report to platform where purchased (Swappa, eBay, etc.)
- File police report if phone was stolen (bring all evidence)
- Contact FTC at ReportFraud.ftc.gov
- Leave honest review to warn other buyers
Final Checklist Before Purchase
- ✓ IMEI checked on multiple databases (not blacklisted)
- ✓ Activation Lock / Google FRP verified as removed
- ✓ Physical condition matches description
- ✓ All features tested and working
- ✓ Phone confirmed unlocked with your carrier SIM
- ✓ Battery health above 80%
- ✓ Original accessories included (if promised)
- ✓ Receipt or proof of purchase provided
- ✓ Seller identity verified
- ✓ Payment method offers buyer protection
Buying a used unlocked phone can be a smart financial decision, but requires careful verification. Follow this guide to protect yourself from scams and ensure you're buying a legitimate device that will serve you well for years to come.