If you buy a phone on a contract base with a specific carrier( service provider i.e airtel, jio...etc). In that case there will be a carrier-imposed “lock” is a software code that prevents your phone from working on another cellular network and won't allow receiving software updates directly from the mobile phone manufacturers.
Unlocked Devices -
you can get service with any carrier on a compatible network. No additional software is added to prevent the device from getting direct updates.
