The upgrade can be downloaded via Samsung Kies desktop software
Android 4.1.2 Jelly Bean has finally reached Samsung Galaxy S III devices purchased via Three UK. The carrier has just confirmed that the update is available for download via Samsung Kies desktop software.However, those who do not want to connect their smartphone to a PC can try to manually pull the upgrade by going to Settings / About phone / Software updates / Update.
The update might not yet be available for all Galaxy S III owners right away, but at least we know that Samsung has already started the rollout.
Those who prefer to download the update via 3G network should know that this method uses data included in their plan. If they have a data limit, it’s recommended to check the My3 account to make sure they have enough data left.