T-Mobile is usually one of the first carriers in the United States to offer major Android upgrades for smartphones in its portfolio. However, this time, the Magenta carrier was outmaneuvered by the competition.

After Sprint and Verizon, T-Mobile announced that it would kick off the rollout of Android 6.0.1 Marshmallow for Samsung Galaxy S6 and Galaxy S6 edge, on April 11.
Unlike other carriers that include some of their own improvements and new features, T-Mobile does not mention anything else except Android 6.0 Marshmallow. This could also mean that the update doesn’t contain the latest security patches released by Google.
The good news is those who capture the update will be able to check which version of security patch they have on their smartphones (February, March or April).
Depending on what variant of Galaxy S6 you own, flat or curved, you will receive Android 6.0.1 Marshmallow baseband version G920TUVU3EPD1 or G925TUVU3EPD1. Naturally, the update is delivered OTA (over the air) in stages, so it should take a few days for it to reach all Galaxy S6 and Galaxy S6 edge devices.
Additional improvements for Samsung Galaxy S6 edge When it comes to changes, both smartphones will benefit from a bunch of new features and improvements, courtesy to Android 6.0 Marshmallow. Samsung Galaxy S6/S6 edge will be able to find the long-awaited Doze mode, special permission app system, and many other enhancements.
On top of that, Samsung added its own major improvements to Galaxy S6 edge, which are supposed to enlarge the area on the second display where users receive notifications. New content specially created for the curved display has been added too.
If you haven’t been notified about the update yet, you can manually check for Android 6.0 Marshmallow by heading to Settings / About device / Software update. If it’s not available, you can try again later.