A used phone can look perfect and still be a bad buy. Check the parts you cannot see.
Before you pay, verify the phone’s identity, lock status, battery, hardware, and actual cellular service. Ten careful minutes can catch problems that a clean screen and a cheap price will not.
The expensive used-phone problems usually are not scratches.
A cracked corner is obvious. A blacklisted IMEI, carrier lock, previous-owner account lock, weak battery, bad microphone, damaged charging port, or wrong storage size can hide behind a phone that looks almost new.
That is why the goal is not to prove the phone is pretty. The goal is to prove that this exact device can become your phone after the seller leaves.
How strict should you be?
Private seller, in person
Do all eight checks before payment. This is the easiest situation to test thoroughly, so there is little reason to skip the basics.
Online marketplace
Favor listings with buyer protection and a real return window. Run the IMEI and full hardware check as soon as the phone arrives, before moving your life onto it.
Refurbished retailer
Read what “refurbished” actually covers, then test the device inside the return period. A grading label is useful, but it is not a substitute for checking the phone you received.
The eight checks to make before you pay.
Match the IMEI to the phone.
The IMEI is the phone’s cellular identity. Pull it from the phone itself, not just a screenshot, box label, or seller message. You can usually find it in Settings or by dialing *#06#.
Do this: compare the IMEI, make/model, and the device in your hand. Dual-SIM phones may show more than one IMEI.
Walk away if: the device description does not match, the seller will not show the IMEI, or the numbers look inconsistent.
Run the IMEI for lost or stolen status.
Use the CTIA Stolen Phone Checker in the U.S. A green result means the device was not flagged on the GSMA Block List at the time of the query.
Do this: run the exact IMEI while you are with the seller, or immediately after an online delivery arrives.
Walk away if: the result says reported lost or stolen. A “clean” result is still a snapshot, not a guarantee about every other issue with the phone.
Verify the carrier lock and network fit.
Unlocked and compatible are related, but they are not the same thing. You want a phone that is allowed to leave its old carrier and actually works with the carrier you plan to use.
Do this: on iPhone, go to Settings → General → About and look at Carrier Lock. Apple says “No SIM restrictions” means the iPhone is unlocked. On Android, lock-status menus vary, so use the seller’s carrier unlock status and test another compatible SIM or eSIM when possible.
Walk away if: the seller says “it should be unlocked” but cannot prove it, especially if you need to activate on a different carrier immediately.
Make sure the previous owner’s account lock is gone.
A factory reset is not enough if the device is still protected by the previous owner’s account.
Do this: on iPhone, do not buy a device that shows iPhone Locked to Owner or otherwise has Activation Lock enabled. On Android, the seller should remove their Google Account before reset so device protection does not block setup for the next owner.
Walk away if: setup asks for the previous owner’s Apple or Google credentials and the seller cannot clear it on the spot.
Confirm the exact model, storage, and repair history.
“iPhone 15” or “Galaxy S24” is not enough. Storage size, model variant, SIM support, and prior repairs can change the value of the phone.
Do this: open the About screen and confirm model name/number and storage. On supported iPhones, check Settings → General → About for Parts and Service History so you can see whether certain parts were replaced and how iOS identifies them.
Walk away if: the listing says one storage size or model and the phone reports another, or the seller gets vague when you find an unexpected repair.
Check the battery and charging.
A cheap phone with a battery replacement due next week is not as cheap as it looked.
Do this: on iPhone, review Battery Health and any battery messages. On Android, battery-health reporting varies, so check any built-in diagnostics the manufacturer provides, confirm the phone charges normally, and price a replacement into the deal if the battery is clearly tired.
Walk away if: the phone will not charge reliably, the screen or back is separating from the frame, or the seller refuses to let you connect a charger.
Test the expensive hardware, not just the screen.
Spend a few minutes trying the parts that become annoying or expensive when they fail.
Do this: test touch across the display, brightness, every camera lens, video, microphone, speaker, vibration, buttons, charging port, Wi-Fi, Bluetooth, and Face ID / Touch ID / fingerprint unlock if the phone supports it.
Walk away if: a camera will not focus, audio cuts out, touch has dead areas, biometric unlock is broken, or the charging port only works when the cable is held at an angle.
Put the phone on real cellular service.
The best final test is boring: make the phone act like a phone.
Do this: when practical, activate a compatible SIM or eSIM, place a call, send a text, and load a webpage over cellular data. If you cannot activate before buying, at minimum run your intended carrier’s compatibility check with the exact IMEI.
Walk away if: the seller is rushing you past the one test that proves the device can actually connect to service.
Run the IMEI before the money moves.
The CTIA checker is free for limited consumer lookups and tells you whether the device is currently flagged as lost or stolen. After that, finish the physical and lock-status checks yourself.
Proceed when the phone proves itself.
- IMEI matches the device and comes back clean.
- Carrier lock status fits the network you plan to use.
- Previous-owner account protection is completely removed.
- Model, storage, and condition match the listing.
- Battery and charging are acceptable for the price.
- Cameras, audio, screen, buttons, and biometrics work.
- You can activate or otherwise verify cellular compatibility.
Do not let a cheap price talk you past these.
- Seller will not provide or let you verify the IMEI.
- Device is reported lost or stolen.
- Activation Lock or Android device protection is still tied to the seller.
- “Unlocked” cannot be verified and you need another carrier.
- Model, storage, or device description does not match.
- Charging, cameras, audio, display, or biometrics show obvious failures.
- The seller is rushing payment before basic testing.
If you buy it, finish the handoff before you leave.
Once the checks are done, have the seller fully erase the phone if they have not already, confirm it reaches the normal setup screen without asking for their credentials, and keep a record of the sale and the IMEI.
If you are buying online, do the same checks during the return window. Do not wait until after you have migrated every photo, app, authenticator, and banking login to discover that the microphone is dead or the phone cannot activate on your carrier.
Frequently asked questions
Is a clean IMEI enough to know a used phone is safe to buy?
No. CTIA says a green result means the device was not flagged on the GSMA Block List at the time of the query. You still need to check carrier lock, account protection, hardware condition, exact model, battery, and cellular compatibility.
How do I know if a used iPhone is unlocked?
Open Settings → General → About and look at Carrier Lock. Apple says “No SIM restrictions” means the iPhone is unlocked. If a carrier is shown instead, the phone is restricted to that carrier until it is properly unlocked.
What if the iPhone says “iPhone Locked to Owner”?
Do not buy it in that state. The seller needs to remove Activation Lock. Apple specifically tells buyers not to take ownership of a used iPhone while Activation Lock is enabled.
What should I check on a used Android before reset?
Make sure the seller removes their Google Account from the phone before the final reset. Google’s device-protection guidance says removing the Google Account turns off that protection. After reset, the phone should not require the previous owner’s credentials to complete setup.
What battery health percentage is too low?
There is no one percentage that makes every used phone a bad buy. On iPhone, review maximum capacity and any battery messages. On Android, battery-health reporting varies. The practical question is whether the battery condition is acceptable for the price after you include the likely cost of replacement.
Should I buy a used phone if I cannot test it first?
Only when the seller or retailer gives you enough protection to make the risk reasonable, such as a clear return window and buyer protection. For an in-person private sale, refusing basic testing is a strong reason to walk away.
A used phone can look perfect and still be a bad buy. Check the parts you cannot see.
Before you pay, verify the phone’s identity, lock status, battery, hardware, and actual cellular service. Ten careful minutes can catch problems that a clean screen and a cheap price will not.
The expensive used-phone problems usually are not scratches.
A cracked corner is obvious. A blacklisted IMEI, carrier lock, previous-owner account lock, weak battery, bad microphone, damaged charging port, or wrong storage size can hide behind a phone that looks almost new.
That is why the goal is not to prove the phone is pretty. The goal is to prove that this exact device can become your phone after the seller leaves.
How strict should you be?
Private seller, in person
Do all eight checks before payment. This is the easiest situation to test thoroughly, so there is little reason to skip the basics.
Online marketplace
Favor listings with buyer protection and a real return window. Run the IMEI and full hardware check as soon as the phone arrives, before moving your life onto it.
Refurbished retailer
Read what “refurbished” actually covers, then test the device inside the return period. A grading label is useful, but it is not a substitute for checking the phone you received.
The eight checks to make before you pay.
Match the IMEI to the phone.
The IMEI is the phone’s cellular identity. Pull it from the phone itself, not just a screenshot, box label, or seller message. You can usually find it in Settings or by dialing *#06#.
Do this: compare the IMEI, make/model, and the device in your hand. Dual-SIM phones may show more than one IMEI.
Walk away if: the device description does not match, the seller will not show the IMEI, or the numbers look inconsistent.
Run the IMEI for lost or stolen status.
Use the CTIA Stolen Phone Checker in the U.S. A green result means the device was not flagged on the GSMA Block List at the time of the query.
Do this: run the exact IMEI while you are with the seller, or immediately after an online delivery arrives.
Walk away if: the result says reported lost or stolen. A “clean” result is still a snapshot, not a guarantee about every other issue with the phone.
Verify the carrier lock and network fit.
Unlocked and compatible are related, but they are not the same thing. You want a phone that is allowed to leave its old carrier and actually works with the carrier you plan to use.
Do this: on iPhone, go to Settings → General → About and look at Carrier Lock. Apple says “No SIM restrictions” means the iPhone is unlocked. On Android, lock-status menus vary, so use the seller’s carrier unlock status and test another compatible SIM or eSIM when possible.
Walk away if: the seller says “it should be unlocked” but cannot prove it, especially if you need to activate on a different carrier immediately.
Make sure the previous owner’s account lock is gone.
A factory reset is not enough if the device is still protected by the previous owner’s account.
Do this: on iPhone, do not buy a device that shows iPhone Locked to Owner or otherwise has Activation Lock enabled. On Android, the seller should remove their Google Account before reset so device protection does not block setup for the next owner.
Walk away if: setup asks for the previous owner’s Apple or Google credentials and the seller cannot clear it on the spot.
Confirm the exact model, storage, and repair history.
“iPhone 15” or “Galaxy S24” is not enough. Storage size, model variant, SIM support, and prior repairs can change the value of the phone.
Do this: open the About screen and confirm model name/number and storage. On supported iPhones, check Settings → General → About for Parts and Service History so you can see whether certain parts were replaced and how iOS identifies them.
Walk away if: the listing says one storage size or model and the phone reports another, or the seller gets vague when you find an unexpected repair.
Check the battery and charging.
A cheap phone with a battery replacement due next week is not as cheap as it looked.
Do this: on iPhone, review Battery Health and any battery messages. On Android, battery-health reporting varies, so check any built-in diagnostics the manufacturer provides, confirm the phone charges normally, and price a replacement into the deal if the battery is clearly tired.
Walk away if: the phone will not charge reliably, the screen or back is separating from the frame, or the seller refuses to let you connect a charger.
Test the expensive hardware, not just the screen.
Spend a few minutes trying the parts that become annoying or expensive when they fail.
Do this: test touch across the display, brightness, every camera lens, video, microphone, speaker, vibration, buttons, charging port, Wi-Fi, Bluetooth, and Face ID / Touch ID / fingerprint unlock if the phone supports it.
Walk away if: a camera will not focus, audio cuts out, touch has dead areas, biometric unlock is broken, or the charging port only works when the cable is held at an angle.
Put the phone on real cellular service.
The best final test is boring: make the phone act like a phone.
Do this: when practical, activate a compatible SIM or eSIM, place a call, send a text, and load a webpage over cellular data. If you cannot activate before buying, at minimum run your intended carrier’s compatibility check with the exact IMEI.
Walk away if: the seller is rushing you past the one test that proves the device can actually connect to service.
Run the IMEI before the money moves.
The CTIA checker is free for limited consumer lookups and tells you whether the device is currently flagged as lost or stolen. After that, finish the physical and lock-status checks yourself.
Proceed when the phone proves itself.
- IMEI matches the device and comes back clean.
- Carrier lock status fits the network you plan to use.
- Previous-owner account protection is completely removed.
- Model, storage, and condition match the listing.
- Battery and charging are acceptable for the price.
- Cameras, audio, screen, buttons, and biometrics work.
- You can activate or otherwise verify cellular compatibility.
Do not let a cheap price talk you past these.
- Seller will not provide or let you verify the IMEI.
- Device is reported lost or stolen.
- Activation Lock or Android device protection is still tied to the seller.
- “Unlocked” cannot be verified and you need another carrier.
- Model, storage, or device description does not match.
- Charging, cameras, audio, display, or biometrics show obvious failures.
- The seller is rushing payment before basic testing.
If you buy it, finish the handoff before you leave.
Once the checks are done, have the seller fully erase the phone if they have not already, confirm it reaches the normal setup screen without asking for their credentials, and keep a record of the sale and the IMEI.
If you are buying online, do the same checks during the return window. Do not wait until after you have migrated every photo, app, authenticator, and banking login to discover that the microphone is dead or the phone cannot activate on your carrier.
Frequently asked questions
Is a clean IMEI enough to know a used phone is safe to buy?
No. CTIA says a green result means the device was not flagged on the GSMA Block List at the time of the query. You still need to check carrier lock, account protection, hardware condition, exact model, battery, and cellular compatibility.
How do I know if a used iPhone is unlocked?
Open Settings → General → About and look at Carrier Lock. Apple says “No SIM restrictions” means the iPhone is unlocked. If a carrier is shown instead, the phone is restricted to that carrier until it is properly unlocked.
What if the iPhone says “iPhone Locked to Owner”?
Do not buy it in that state. The seller needs to remove Activation Lock. Apple specifically tells buyers not to take ownership of a used iPhone while Activation Lock is enabled.
What should I check on a used Android before reset?
Make sure the seller removes their Google Account from the phone before the final reset. Google’s device-protection guidance says removing the Google Account turns off that protection. After reset, the phone should not require the previous owner’s credentials to complete setup.
What battery health percentage is too low?
There is no one percentage that makes every used phone a bad buy. On iPhone, review maximum capacity and any battery messages. On Android, battery-health reporting varies. The practical question is whether the battery condition is acceptable for the price after you include the likely cost of replacement.
Should I buy a used phone if I cannot test it first?
Only when the seller or retailer gives you enough protection to make the risk reasonable, such as a clear return window and buyer protection. For an in-person private sale, refusing basic testing is a strong reason to walk away.