Following the update - which can hit your T-Mobile Galaxy S7 over the air any time now - the Android version remains 6.0.1 Marshmallow, but the Baseband version changes from G930TUVU1APB6 to G930TUVU1APB8 on the regular Galaxy S7, and from G935TUVU1APB6 to G935TUVS2APB8 on the S7 edge.
Tomorrow, March 18, Verizon will start rolling out a similar security update to its Samsung Galaxy S7 and S7 edge. We assume that AT&T and Sprint Galaxy S7 owners will soon get this update as well. As always, you can manually check if the update is ready for your Galaxy S7 handset by going to Settings ->About device -> Software update.
As you probably know, Samsung's new flagship smartphones are available to buy since earlier this month. You can take a closer look at them and their features by checking out our Galaxy S7 review and our Galaxy S7 edge review.
sources: T-Mobile (Galaxy S7, S7 edge), Verizon (Galaxy S7, S7 edge) via Droid-life, Phandroid