How to check a used phone before you buy it

Meet somewhere with Wi-Fi, or bring a hotspot, and allow about 15 minutes. Do the account checks first: if they fail, nothing else matters.

Make sure the seller’s account is gone

iPhone

1. Apple’s advice is plain: if the iPhone is Activation Locked, don’t buy it. If you see iPhone Locked to Owner, ask the seller to enter their password to turn off Activation Lock.
2. A seller who is not there can remove the lock remotely: at icloud.com/find they select the device, then Remove This Device.
3. In Settings > General > About, check Carrier Lock. No SIM restrictions means the iPhone is unlocked.

Android

1. Factory Reset Protection keeps a reset phone tied to the Google Account that was on it. Google says the protection turns off when the Google Account is removed from the device, so ask the seller to remove it before resetting the phone.
2. On a Samsung phone, Samsung’s path is Settings > Accounts and backup > Manage accounts > Remove account.
3. If the phone asks for the previous owner’s account after a reset, do not buy it.

Check the battery and the repair history

• iPhone 15 and later: Settings > Battery > Battery Health. iPhone 11 to 14: Settings > Battery > Battery Health & Charging.
• iPhone: Settings > General > About can show a Parts and Service History section, listing replaced parts as Genuine, Unknown, Unverified or Used.
• Google Pixel 8a and later: Settings > Battery > Battery health reads Normal or Reduced. Reduced means the battery holds less than 80% of its original capacity.
• Samsung Galaxy: Settings > Device care > Battery shows battery health. For a wider check, run Samsung Members > Discover > Diagnostics > Phone diagnostics > Test all.

Test the screen, sound and cameras

Open these tests in the phone’s own browser:

1. Dead Pixel Test: step through the colors full screen and look for dots that stay black or lit, or tinted patches. On an OLED screen, check for burn-in with the Burn-In Test.
2. Touch Screen Test: paint every cell. A strip or corner that does not respond is a fault.
3. Speaker Test: play each side, then listen at full volume for rattles or crackling.
4. Microphone Test: speak, and the meter should rise.
5. Webcam Test: check the front and the back camera, switching between them in the Camera list.
6. Gyroscope Test and, on Android, the Vibration Test: the readings should move as you tilt the phone, and the motor should buzz.

Check the hardware by hand

• Press every button, plug your cable into the charging port and check that the phone charges.
• If you can, put your SIM in and make a call.
• Look along the edges. A screen lifting away from the frame or a bulging back can mean a swollen battery: do not buy it.

Check the IMEI

Dial *#06# to show the IMEI, or on an iPhone find it in Settings > General > About. Compare it with the number on the box, if there is one. GSMA’s Device Check service, which shows whether a phone has been reported lost or stolen, is for businesses and law enforcement; GSMA tells consumers to contact their wireless provider.