Today T-Mobile has finally commenced the rollout of Android 6.0 Marshmallow to the Galaxy S5 units it's sold. Samsung's flagship smartphone from two years ago is thus in the process of receiving access to the latest version of Android. As always in these cases, keep in mind that the rollout is staged and it may take a few days for all devices to get the update notification. The new release is software version G900T3UVU1GPE1 or G900TUVU1GPE1 depending on which Galaxy S5 model you have. In both cases, the download should be around 1GB in size, so you will need to fetch it via Wi-Fi....
Source: http://www.gsmarena.com/tmobile_releases_marshmallow_update_for_the_galaxy_s5-news-18362.php
