The unlocked Samsung Galaxy S6 is the latest handset to get the Android 5.1.1 Lollipop update, the software update has been released for the S6 with the model number SM-G902I.
The Android 5.1.1 Lollipop update is around 609MB in size and the update takes the software to version G920IDVU2COF8.
You can check to see if the Android 5.1.1. Lollipop update is available for your unlocked Samsung Galaxy S6 smartphone from the setting menu. The update is available as an over the air update and should be available for devices now.
The update brings a range of bug fixes, performance improvements and some minor new features to the Galaxy S6.
Source Droid Life