Samsung began upgrading its Galaxy S5 to Android 6.0 Marshmallow two months ago, and as with many of its other devices, the update is slowly making its way around the world.
In the US, Sprint updated its Galaxy S5 in early April, and it's not at all clear what's taken T-Mobile so long to get around to doing so as well. Nonetheless, T-Mobile has finally stopped dragging its feet, and has begun rolling out Marshmallow to Samsung's 2014 flagship.
The update, which is based on Android 6.0.1, bumps the Galaxy S5's software version up to G900T3UVU1GPE1 or G900TUVU1GPE1, depending on the exact model.
Google originally released Marshmallow over seven months ago, but it's only made its way to 7.5% of Android devices so far. Meanwhile, Google is already working on Android 7.0, which is expected to arrive later this summer.