Phone Check: Used Phone Test

Phone test for buying or selling a used phone: 26 hardware tests, one screen at a time, and a report with the numbers behind every result.

▶ BUYER RE-CHECK WITH THE SELLER'S QR
• The seller shows the report's QR code; the buyer scans it in Buyer re-check.
• 10 core tests run again on the phone in front of them: touch grid, colour screens, loudspeaker, microphone, vibration, both cameras, charging port, volume buttons, fingerprint / face unlock.
• Seller's result and today's side by side: unchanged ✔, worse now ⚠.
• Model, codename, system level and build fingerprint hash: same model and build, system updated, or a different phone.
• You see whether the QR still matches its 10-character code.

▶ THE SENSORS CHECK EACH OTHER
• Loudspeaker: three tones in a random order; the microphone must hear all three, in that order, at least 12 dB above the noise.
• Microphone: a silent mic is told apart from a refused permission; your voice must be 20 dB above the room.
• Vibration: the accelerometer feels the pattern on a table.
• Light and proximity: cover the sensor or wave a hand; the reading must change.
• Volume keys, power key and charging port are detected when you press them or plug in.
• You are asked when the automatic check can't confirm a result. The speaker fallback plays 2 to 5 random beeps for you to count.

▶ SHOWN VS ACTUAL
• The system version the phone shows vs the system level it really runs.
• Memory read from the kernel vs the RAM the seller claims; storage, real rear photo megapixels (with a pixel binning note) and model vs the ad.
• A difference reads "Doesn't match" with a hint to compare in Settings.

▶ 26 TESTS
• Screen: colour pages (tap to mark spots), grey pages for burn-in, touch grid, multi-touch.
• Loudspeaker, earpiece, microphone, vibration, accelerometer, gyroscope, compass, barometer, light, proximity.
• Flashlight, rear and front camera (black-picture check, photo size, sharpness index).
• Buttons, charging port, battery, Wi-Fi, Bluetooth, GPS satellites, fingerprint / face unlock, SIM.

▶ A REPORT YOU CAN SHARE
• Each item: passed, failed, couldn't check (with the reason) or not present, plus numbers and what to do next.
• Share a PDF or an image card with the code and QR. Add a seller note and the last 4 IMEI digits, typed by you.
• The newest 50 reports stay on this phone. 12-item hand-over checklist.

▶ GOOD TO KNOW
• "Passed" needs a measurement above its threshold; "failed" means no response or you confirmed the problem; in between is "couldn't check".
• The speaker test shows that sound comes out. Buzzing and rattling are your call.
• Some phones switch the proximity sensor on just during calls (then: "couldn't check").
• Battery values are what the phone reports. Phones don't give apps the battery's wear level, so none is shown; the full-charge estimate can be off by 15 % or more.
• The report code shows whether a report was changed after it was made. On its own it proves nothing: re-check the phone in person.
• Not checked: sudden power-offs, overheating, water damage, replaced parts, call quality, extra lenses, NFC. Dead pixels are found by your eyes.
• The IMEI digits are typed by you. Test photos and recordings are not kept after their test; location is used for the GPS test alone.
• No sign-up; reports leave the phone when you share them.
• Ads appear on the three tabs, at start-up and sometimes when you return to the tabs, never during a test, on an open report or in a re-check.