Buying a used phone: what to check

Where to buy

Refurbished phones from a shop or the maker usually come with a warranty and a new battery or a battery-health guarantee. Private sales are cheaper but you need to do the checks yourself, in person, before paying.

1. It must not be locked to an account

This is the most important check. A phone still linked to someone's Google account (Factory Reset Protection) or Apple ID (Activation Lock) cannot be set up by you.

• Ask the seller to factory-reset the phone in front of you and check that the setup screen appears without asking for their account.
• On an iPhone, Settings → your name should show no account before the reset, and "Find My" must be off.

2. Check the IMEI

Dial *#06# to show the IMEI. It should match the box and the settings. Many countries and operators have an online IMEI check for phones reported lost or stolen; a blacklisted phone won't work on mobile networks.

3. Hardware checks

• Battery health: iPhone Settings → Battery → Battery Health; on Android, look in Settings or the maker's diagnostics app. Below 80% means a replacement is due soon.
• Screen: look for dead pixels, burn-in (ghost images on a white or grey background) and touch problems; drag an app icon across the whole screen.
• Cameras, microphones, speakers: record a short video with sound and play it back.
• Charging port: plug in a cable; it should start charging immediately and not wobble.
• Buttons, fingerprint or face unlock, SIM tray, Wi-Fi and Bluetooth.
• Calls: put your SIM in and make a call, to rule out a network lock.

4. How long will it get updates?

Look up the model's software support period on the maker's website. A cheap phone that stops getting security updates next year is a poor deal.

5. Paying safely

Meet in a public place, ideally a shop or the seller's operator store. Avoid paying in advance for a phone you haven't seen, and get a written receipt with the IMEI on it.