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How to tell if a used phone is trustworthy before buying it

Updated in 2026 · 6 min read

Buying a used phone can save you quite a bit of money, but it also has its risks: blocked phones, worn-out batteries or devices with pending financing that stop working after a few days. Before taking the plunge, there are a few simple checks you can do yourself, with no technical knowledge, to make sure the phone you're about to buy is trustworthy.

In this article:

  1. Check the phone's IMEI
  2. Rule out it being blocked for theft or pending financing
  3. Check the battery's condition
  4. Check it has no linked account and review its physical condition

1. Check the phone's IMEI

The IMEI is the number that uniquely identifies each phone, and it's your first tool for checking that the device is legitimate. You can get it by dialing *#06# on the call keypad, or by checking it under Settings → About phone (on Android) or Settings → General → About (on iPhone). Once you have it, compare it with the number printed on the original box or on the purchase invoice, if the seller kept either one. If the numbers don't match, if the seller has no documentation for the phone at all, or if they seem evasive when you ask about it, it's better to be wary and look for another offer.

2. Rule out it being blocked for theft or pending financing

With the IMEI in hand, the next step is to check that the phone isn't reported as stolen and has no financing pending payment. Many carriers let you check the IMEI's status on their own website, and there are also independent services like imei.info where you can enter the number and see basic information about the device. Keep in mind that if the phone was bought in installments and the previous owner stops paying, some carriers can remotely block the device even after you've bought it, so also ask the seller directly whether the phone is fully paid off.

3. Check the battery's condition

The battery is one of the parts that wears out most with use, and replacing it has a cost worth factoring into the price negotiation. On an iPhone you can check its real condition at Settings → Battery → Battery Health & Charging, which shows the maximum capacity compared to when it was new; below 80% you'll already notice noticeably shorter battery life. On Android there's no menu that's quite as direct, but you can dial the code *#*#4636#*#* to access battery information, or install a diagnostic app like AccuBattery to see its health status. Ask the seller to let you check it before closing the purchase.

4. Check it has no linked account and review its physical condition

One of the most common problems when buying used is that the phone is still linked to the previous owner's Google or iCloud account, which triggers an activation lock and can leave the device useless as soon as you restart it. The most reliable way to check this is to ask the seller to do a factory reset in front of you: if, once it's done, the phone asks for the password of an account that isn't yours, you shouldn't buy it. Also use that moment to check the screen for scratches, dead pixels or stains, test the physical volume and power buttons, check the camera and speaker, and verify that it charges normally.

✔ With the IMEI checked, the battery reviewed and the phone factory-reset in front of you, you have reasonable guarantees that the purchase is safe.
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Frequently asked questions

How do I know if the IMEI of a used phone is the right one?

Dial *#06# on the phone itself or check the number under Settings → About phone, and compare it with the one printed on the original box or on the purchase invoice. If the seller has neither the box nor the invoice, or the IMEI doesn't match, that's a red flag and it's best not to go ahead with the purchase.

How do I check if a phone is blocked due to theft or pending financing?

You can enter the IMEI on your carrier's website or on services like imei.info to see if the device appears reported as stolen or lost. It's also worth asking the seller directly if the phone has any outstanding installment payments, since many carriers can remotely block the device if there's unpaid financing.

Is it safe to pay cash for a used phone from a stranger?

It's not the safest option. Whenever possible, it's better to use platforms that hold the payment until you confirm the phone works correctly, rather than paying in cash before checking everything. If you do meet in person, do it in a public place and check the phone calmly before handing over the money.

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