not locked

an opportunistic thief entered the property through an unlocked door

(of a mobile phone) capable of operating on the network of any chosen carrier

with an unlocked phone you can use SIM cards from any service provider

undo the lock of (something), typically with a key

he unlocked the door to his room

use a password or other form of authentication to access the full functionality or data of (a computer, mobile phone, file, etc.)

when you unlock your phone, you're presented with the ‘home screen’—the interface that shows off all your apps