The second-hand phone market has become one of the few genuinely good deals in consumer technology. A flagship handset two or three years old typically costs a third of its launch price, and because phone hardware stopped improving dramatically around 2020, the practical difference between it and a new mid-range device is small. The risks are real but they are also finite, and they can be checked in about ten minutes.
Check the security support window first
This is the single most important number and the one most listings omit. A phone that no longer receives security updates should be treated as a disposable device rather than a primary phone, because it will accumulate unpatched vulnerabilities and, increasingly, banking and authentication apps will refuse to run on it.
Apple supports iPhones with iOS updates for roughly five to seven years from launch. Google commits to seven years of updates on recent Pixel models. Samsung offers between four and seven years depending on tier and year. Manufacturers selling in the UK are now required to publish a defined support period under the product security regime described in the government product security guidance, which makes this far easier to verify than it was.
Work out the launch year of the model, add the manufacturer commitment, and ask whether the remaining window is long enough to justify the price. A phone with eighteen months of updates left is not a bargain at any price if you intend to keep it for four years.
Check the IMEI
Every handset has a unique fifteen-digit IMEI, visible by dialling star hash zero six hash or in the settings under about. A phone reported lost or stolen is blocked on UK networks and will never make a call again regardless of which SIM you insert. The industry runs a checking service through CheckMEND, and the police-backed Immobilise property register is the other reference point. A seller unwilling to provide an IMEI before payment is telling you something.
Separately, ask whether the phone is network-locked. Locking is much rarer than it used to be, since new handsets sold in the UK have been supplied unlocked since December 2021, but older stock still circulates.
Check that the account is signed out
An iPhone still linked to a previous owner’s Apple account is an expensive paperweight: activation lock cannot be bypassed, and the original owner is the only person who can remove it. The equivalent on Android is a Google account lock after factory reset. Insist on seeing the phone fully reset and sitting on the initial setup screen before money changes hands. If you are buying remotely, ask for a photograph of that screen.
Assess the battery honestly
Battery health is the component that actually degrades. On an iPhone the figure is in settings under battery health and a reading below about eighty per cent means a replacement is due. Android reporting is inconsistent and often requires a third-party app. A battery replacement at an independent repair shop costs between forty and eighty pounds for most models, which is worth factoring into the price rather than treating as a deal-breaker.
Inspect for water and screen damage
Look at the screen with it switched off in bright light, which reveals scratches invisible on a lit display, and then with a white image, which reveals dead pixels and burn-in on OLED panels. Check that the frame is not bowed, that the camera glass is intact, and that the charging port is clean and firm. Ask directly whether the phone has been repaired and with what parts; non-genuine screens are common and usually visible as slightly wrong colour temperature.
Where you buy changes your rights
This is the part people ignore and it matters more than any hardware check. Buying from a business, including refurbishers and network stores, brings the Consumer Rights Act into play: the phone must be as described, fit for purpose and of satisfactory quality, and you have a short-term right to reject. Buying privately from an individual brings almost none of that. The Citizens Advice consumer guidance sets out the difference clearly, and the practical implication is that a refurbished phone from a dealer at thirty pounds more than a private sale is usually the cheaper purchase once risk is priced in.
Refurbished grading is unregulated, so grade A from one seller may mean something different from grade A elsewhere. Read the definition rather than the letter, and prefer sellers offering at least twelve months of warranty.
The short version
Confirm the model has years of security updates remaining. Check the IMEI against a blacklist service. See it reset and signed out. Read the battery health. Inspect the screen off and white. Buy from a business if the price difference is small. That sequence eliminates nearly every way this transaction goes wrong.
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