SIM lock: what to do with a phone locked to one operator
A SIM lock (carrier lock) is a software restriction that makes a phone work only with a particular operator's SIM cards. Phones sold on contract in the US, Japan and other countries are often locked this way.
In plain words
A SIM-locked phone is like a bike chained to one bike rack: you can only ride where the rack owner allows. The operator sold you the phone cheaply but keeps the key to the lock until you meet the terms of your contract.
How it works
- The operator activates the lock in the firmware or on its servers.
- The phone accepts only that operator's SIM cards.
- Another SIM brings up a "SIM not supported" message.
- Once the contract is paid off, the operator can remove the lock.
- Unofficial unlocking methods are risky and can relock the phone.
Where you'll see it
Locked phones most often come from the US (contract iPhones and Galaxies), Japan and the UK. They also turn up among used and grey-import phones, including "R-SIM" models with an adapter sticker.
Does it matter when buying
A lot, if you are buying a used phone or ordering from abroad. Test your SIM in the phone before buying and check its lock status. Phones unlocked "with an R-SIM" often work unreliably and can stop working after an update.
Myths
- Myth: A factory reset removes a SIM lock. Reality: No, the lock stays.
- Myth: Unlocking is hacking. Reality: Official unlocking by the operator is a legal procedure.
FAQ
How do I check whether a phone is locked?
Insert another operator's SIM or check the IMEI with an official service.
What is an R-SIM?
An adapter sticker that bypasses the lock; it is unreliable.
Can a US phone be unlocked?
Officially, through the operator once the contract terms are met.