A used iPhone in good condition is one of the best-value purchases in consumer electronics. Apple's long software support cycles, premium build quality, and high resale value mean even a two or three year old iPhone is a capable daily driver. But the used iPhone market also attracts fraud — and an unthorough buyer is at risk.
This checklist covers every step, in order, that you should complete before buying any used iPhone.
Before Meeting the Seller — Remote Checks
Do these checks using only the IMEI. Ask the seller to provide it (they can find it via *#06#). You can run all of these before seeing the device in person.
1. IMEI Blacklist Check
Tool: DeviceDecoded Lost & Stolen Database
Enter the IMEI. The result must show Clean. A blacklisted iPhone cannot connect to any mobile network and is effectively useless as a phone. Do not meet the seller if this shows blacklisted.
2. iCloud Activation Lock Check
Tool: DeviceDecoded iCloud Lock Check
Enter the IMEI. The result must show No Activation Lock. An active iCloud lock means the phone cannot be set up without the previous owner's Apple ID and password. Never pay for an iPhone with active iCloud lock.
3. Find My Status
Tool: Included in the iCloud Lock Check
Find My being active confirms iCloud lock is applied. Ask the seller to turn Find My off in Settings > [their name] > Find My > Turn Off Find My before the transaction completes.
4. Carrier Lock Status
Tool: DeviceDecoded Carrier Lookup
Identify the original carrier. If you need an unlocked phone, confirm the device is unlocked. If it is locked to a carrier, verify you will be using it on that carrier — or factor in the unlock process.
5. Warranty and AppleCare Status
Tool: DeviceDecoded Apple Coverage Check
Enter the IMEI or serial number. Note:
- Purchase date (does this match what the seller claims?)
- Warranty expiry (how much warranty remains?)
- AppleCare+ status (is extended coverage active and what does it cover?)
Remaining warranty adds real value. An iPhone with 18 months of AppleCare+ remaining is worth more than one with expired warranty — price accordingly.
6. Device Model Verification
The TAC code (first 8 digits of the IMEI) confirms the exact model. If a seller claims a device is an iPhone 15 Pro but the IMEI check returns iPhone 15 (non-Pro), the claim is false.
At the Handover — Physical Checks
Do these when you physically have the device.
7. IMEI Cross-Reference
Dial *#06# on the device and compare the IMEI displayed on screen to:
- The IMEI on the original box (if present)
- The IMEI the seller shared with you remotely
All three must match. Mismatched IMEIs indicate tampered hardware.
8. Face ID / Touch ID Functionality
Test biometric authentication. Face ID or Touch ID being non-functional can indicate a repair that was not done through Apple (which disables these features without an Apple-certified repair or software re-pairing).
9. Screen Quality
Check for:
- Dead pixels (look at a solid white screen)
- Burn-in (look at a solid grey screen)
- True Tone uniformity (no blotchy brightness distribution)
- Signs of a non-Apple screen replacement (yellow tint on iPhone X and later)
10. Battery Health
Settings > Battery > Battery Health & Charging. Note the Maximum Capacity percentage.
- 100-85%: Excellent — device has barely been used or battery was replaced
- 84-80%: Good — typical for a 1-2 year old device
- 79% and below: Consider negotiating price or expect to pay for battery replacement (~£89 from Apple)
11. Water Damage Indicator (older iPhones)
On iPhones with a removable SIM tray (pre-X models): Look at the SIM tray slot with a torch. There should be a white dot (the liquid contact indicator). A red or pink dot means the device has been exposed to liquid.
Newer iPhones (X onwards) are IP67 or IP68 rated. Check for corrosion in the charging port regardless.
12. Camera and Sensors
Test front and rear cameras. Check:
- Front camera (selfie and Face ID sensor)
- Rear cameras (main, ultra-wide, telephoto — check each in Camera app)
- Flashlight
- Proximity sensor (screen turns off during a call)
- Accelerometer (rotate device to test orientation lock)
13. Network Connectivity
Insert your SIM and test:
- Call functionality
- SMS
- Mobile data
- Wi-Fi (connect to a network)
14. Charge Port
Plug in a charger cable. Confirm the device charges and that the port is not loose or corroded.
At the Device Handover — Completing the Transfer
15. Have the Seller Remove Their Apple ID
In your presence, the seller should:
- Go to Settings > [their name]
- Scroll to the bottom and tap Sign Out
- Enter their Apple ID password
- Choose to keep or remove data as appropriate
After sign-out, Find My is disabled and iCloud lock is removed.
16. Factory Reset the Device (Optional but Recommended)
After the seller signs out, you can reset the device: Settings > General > Transfer or Reset iPhone > Erase All Content and Settings
The device should start fresh and proceed to the normal "Hello" setup screen — without asking for the previous owner's Apple ID. If it asks for an Apple ID, the seller has not properly signed out.
17. Get a Receipt
Get written confirmation (text, email, or paper) of:
- Device model and IMEI
- Purchase price
- Date of transaction
- Seller's contact details
This protects you if the device is later blacklisted or is discovered to be stolen.
After Purchase
- Set up with your own Apple ID immediately
- Enable Find My to protect your device
- Register the device with AppleCare if still within the 60-day enrolment window
- Note battery health as a baseline for future reference
Following this checklist takes less than 30 minutes and protects what could be a significant purchase. The most important checks — blacklist, iCloud lock, carrier lock — take under two minutes using DeviceDecoded's IMEI Check tool.