The biggest used-phone mistake is treating one successful check as proof of the whole device. A clean IMEI, working screen or original-looking box cannot replace account, function, seller and condition checks.
Paying before account locks are resolved
For iPhone, complete the Activation Lock check through the setup process. For Android, make sure the previous accounts are removed before reset. Do not accept a promise that the seller will fix it later.
Using IMEI as a guarantee
An IMEI result can show a known block at the time of checking. It cannot prove ownership or prevent a later report. Match identifiers and keep seller evidence.
Ignoring battery and repair history
| Evidence | Question |
|---|---|
| Battery information | Is it manufacturer data, a diagnostic category or an app estimate? |
| Parts history | Which part was replaced and does every related feature work? |
| Frame and seals | Could impact or previous opening affect reliability? |
| Seller description | Is the condition written clearly enough to enforce? |
Failing to test normal use
Test charging, calls, microphones, speakers, cameras, touch, biometrics, buttons, Wi-Fi and Bluetooth. Use the full second-hand phone test rather than checking only that it powers on.
Overpaying for private-sale risk
Compare with a refurbished business seller offering returns and warranty. A small private-sale discount may not justify an uncertain battery and no practical return route.
Letting a factory reset hide useful evidence
Inspect battery information, parts history and normal functions before the seller erases the device. Then complete the reset and account-lock check before paying. Both stages matter; doing only one leaves a gap.
Testing only on Wi-Fi
Where safe and permitted, confirm calls, mobile data and the relevant SIM functions. A phone can browse on Wi-Fi while having a blocked IMEI, damaged antenna or incompatible regional variant.
Ignoring the return journey
For delivery purchases, know who pays return postage, which service may carry a lithium-battery device and how the condition will be evidenced. A cheap phone can become expensive if a dispute requires uninsured international return.
Related guidance: Use Buying a Phone to choose the right route. The Complete Phone Buying Guide provides the full checklist for comparing the available options.
Sources checked
Information checked on 26 July 2026. Retailer, provider and manufacturer terms can change, so confirm the current wording before acting.
