How to Check a Used iPhone Before You Buy: Activation Lock, IMEI and Replaced Parts

1. Activation Lock comes first

If the seller’s Apple Account is still signed in, the phone is useless to you. After a reset it will stop on the iPhone Locked to Owner screen and ask for their password.

Open Settings. If a name appears at the top, the seller is still signed in.
Ask them to go to Settings → [their name] → Sign Out and enter their password, then Settings → General → Transfer or Reset iPhone → Erase All Content and Settings. Watch them do it.
When the phone restarts on the Hello screen, it is ready for a new owner.

Never accept “I’ll remove it later” or a phone that is already on a lock screen you can’t get past. Apple only removes Activation Lock for the original owner with proof of purchase.

2. Check the IMEI

Find the IMEI in Settings → General → About, or dial *#06#. It should match the number on the SIM tray and the box, if there is one.
Check it with a blacklist checker such as the free IMEI check on Swappa or the CTIA Stolen Phone Checker in the US. It shows whether the phone has been reported lost or stolen, or has unpaid finance that can get it blocked.

3. Carrier lock

In Settings → General → About, look for Carrier Lock. No SIM restrictions means the phone is unlocked. Anything else means it only works with one carrier until that carrier unlocks it. If you can, put your own SIM in and make a call.

4. Parts and service history

Scroll down Settings → General → About to Parts and Service History. If the section isn’t there, iOS hasn’t recorded any replaced parts. If it is there:

Genuine Apple Part means the part was replaced by Apple, an authorized provider, or with Apple’s own repair process.
Unknown Part means a non-genuine or unverified screen, battery or camera. It may work fine, but it can affect display quality, True Tone, battery readings or Face ID, and it lowers the value.
On iPhone 15 and later, Used means a genuine part that came from another iPhone.

Older models show less: some list only the battery and display. A missing section on an older iPhone is not proof that nothing was replaced, so check the screen quality too.

5. Battery health

Go to Settings → Battery → Battery Health. Below 80% means a replacement will be due soon, so factor in the cost. On iPhone 15 and later, Settings → General → About also shows the cycle count. Our battery health guide explains what the numbers mean.

6. Test the hardware

Open mxmob.com/check in Safari on the iPhone you are buying and tap Test all. It walks through the screen, touch, speakers, earpiece, microphones, every camera, motion sensors, GPS, Wi-Fi and buttons in about five minutes. Also check these by hand:

Face ID or Touch ID: set it up with your own face or finger. A failed Face ID setup often follows a drop or a bad repair.
Charging: plug it in and check that it starts charging. Our battery test shows the charging state.
True Tone: in Settings → Display & Brightness, a missing True Tone switch can mean a replaced screen.
The body: look for a lifted screen edge, a bent frame, or gaps around the display. A screen that lifts can mean a swollen battery.

7. Stay safe while buying

Meet somewhere public and busy, and bring a charger and your own SIM.
Avoid payment methods with no protection, such as gift cards or wire transfers.
Get the seller’s name and a written receipt with the IMEI on it.

For Android phones and everything else, the full used phone checklist covers the rest.