How to unlock a phone: carrier, screen and account locks
A phone can be locked in three different ways. Each one is removed differently, and only some of them can be removed by the person holding the phone.
Carrier lock
A carrier-locked phone only works with SIM cards from the carrier that sold it. Only that carrier can unlock it, usually once the phone is paid off and has been active on its network for a set time. Ask the carrier for its unlock policy.
Screen lock: passcode, PIN or pattern
If you know the passcode, you can turn the screen lock off in the phone's settings. If you have forgotten it, the phone has to be erased and set up again, which deletes any data that is not backed up. Apple and Google publish the steps for their phones.
Account lock: Activation Lock and Factory Reset Protection
iPhones have Activation Lock, which is tied to the owner's Apple ID. Android phones have Factory Reset Protection, which is tied to the owner's Google account, and on Samsung phones also to the Samsung account. After a reset, the phone asks for that account's password. Only the owner can turn it off, by signing out of the account before the phone changes hands. Apple can also remove Activation Lock for the original owner with proof of purchase.
Before you buy a used phone
- Ask whether the phone is unlocked, and which carrier it was used with.
- Ask for the IMEI and check that it is not reported lost or stolen and has no unpaid device balance.
- Make sure the seller has signed out of their Apple ID or Google account, so the phone does not ask for their password after a reset.
- Check the model number, so you know the phone supports your carrier's network.
The Samsung Galaxy A53 page has a model-by-model checklist for that phone.
Before you sell or trade in a phone
- Back up your data.
- Sign out of your Apple ID or Google account. This turns off Activation Lock or Factory Reset Protection.
- Erase the phone and remove the SIM card.
To list a phone for sale, see how to sell phones on FlexEmarket.