This is probably best for your Wi-Fi rather than mobile data as the download comes in at a hefty 1988.79MB, with firmware version G965USQU3CSAB for the S9 Plus and G960USQS3CSAB for the S9 standard.
Once you’re updated, you can expect the typical Android Pie features liked adaptive battery and new gesture navigation, as well as a revamped version of Samsung’s One UI skin. What’s more, T-Mobile has included support for the RCS 1.0 universal profile, putting the S9 and S9 Plus among the few handsets to embrace the new messaging standard. You can read up on everything you need to know about RCS at the link.
It might take you a few days to receive the upgrade however, as these rollouts tend to happen in stages. If you haven’t been notified already, check your software update page in your phone’s Settings menu to see if it’s ready for the download.
This rounds off the Galaxy S9 and S9 Plus Pie update for the major U.S. carriers and we’re now only waiting on for it to hit the unlocked models. Let me know if the comments if you’ve received Pie yet and what you think of the new software!