Checklist: What to Check Before Buying a Used iPhone

Most guides to buying a used iPhone start with cosmetic condition. That is the least important thing. Three checks decide whether the phone will work for you at all, and if any of them fails, the condition does not matter.

Do these three before you discuss anything else.

The three that decide everything

1. Activation Lock must be off. If the phone is still tied to the seller's Apple Account, it is a paperweight. You cannot set it up, and no amount of resetting removes it.

Ask the seller to go to Settings, tap their name, Find My, Find My iPhone and show you it is switched off. Better still, have them fully erase the phone in front of you: Settings, General, Transfer or Reset iPhone, Erase All Content and Settings. It should reboot to the "Hello" setup screen. If it asks for an Apple Account password to proceed past setup, walk away.

A seller who says they will remove it later is asking you to pay for a brick and trust them to fix it afterwards. They will not.

2. The IMEI must be clean. The IMEI is the phone's unique identity. Get it by dialling star hash zero six hash on the keypad, or from Settings, General, About. Check it three ways:

• It matches the phone. Compare the number on screen with the one in Settings and, if there is a box, the one on the box. A mismatch means parts, a swap, or something worse.
• It is not blacklisted. A blacklisted IMEI means the phone has been reported lost or stolen and will be blocked from UK networks. It may work on wifi and be useless as a phone. Free GSMA blacklist checkers exist online; for a stronger UK check, CheckMEND draws on police and insurance data for a small fee.
• It is not carrier locked, unless you are happy with that network. Ask which network it is locked to, or check Settings, General, About, Carrier Lock, which should read "No SIM restrictions".

3. Battery health. Settings, Battery, Battery Health and Charging. Anything below about 80 percent means a replacement is due soon, which is a real cost. Also look at Cycle Count where available. If the phone shows a "Service" or "Unknown Part" message, the battery has been replaced with a non-genuine part, which is worth knowing and worth a discount.

While you are there, check Settings, General, About for any "Unknown Part" warnings against the display, camera or battery. Apple flags non-genuine replacements, and it is the fastest way to spot a repaired phone being sold as original.

The physical checks

• Screen. Look at it switched off under good light, which shows cracks and scratches the wallpaper hides. Switch to a white background and look for dead pixels, discolouration and burn-in. Press gently around the edges for lifting.
• Every button. Power, both volume buttons, the action button or mute switch. Test them all, twice.
• Both cameras and the flash. Take a photo with each lens including ultra-wide and telephoto, record a video, use the torch. Look for dust or condensation behind the glass.
• Face ID or Touch ID. Have the seller remove theirs and set yours up, or at minimum confirm the feature enrolls. A failed Face ID module is expensive.
• Charging and sound. Plug it in and confirm it charges. Play audio through the speaker, make a test call, check the microphone with a voice memo.
• Water damage. Check the SIM tray slot with a torch. A red indicator inside means water ingress. Corrosion around the charging port is another tell.
• Wifi, Bluetooth and mobile data. Connect to something. Put your own SIM in if you can and make a call.

Questions worth asking

• Why are you selling it, and how long have you had it?
• Has it ever been repaired, and if so by whom?
• Do you have the box, the receipt, or any proof of purchase?
• Is it on any finance or contract? A phone still on a contract can be blocked later, even if it works today. This catches people out regularly.

Practical rules

• Meet somewhere with wifi, power and people. A supermarket cafe works well, because you can actually complete the checks. See where to meet a buyer safely.
• Never pay before the phone is erased and set up in front of you.
• Photograph the IMEI before money moves.
• Be realistic about the price. A current-generation iPhone at half the market rate is either locked, stolen, or not the phone in the photos.

What none of this tells you

Every check here is about the device. None of it tells you about the person.

A phone can pass all three critical checks on the day and still be reported stolen the following week, at which point it is blocked and you have no recourse against a seller you cannot name. The device checks protect you from a phone that is already flagged. They do nothing about one that has not been reported yet.

Chainr covers the other half. Both buyer and seller verify their real identity with a government ID and face check before meeting, you record the item and its IMEI, and you seal the handover in person with a six digit code. You both keep a timestamped certificate showing the item, the price and both verified names, so if the phone is ever questioned you can show exactly who sold it to you.

Related: how to safely sell your iPhone privately, what "ID verified seller" means, is Facebook Marketplace safe.