I have the S21 in hand and activated. Loving it so far, after the latest update. It came with a Sprint SIM installed, but I moved the SIM from my old phone over to it, like the paper they sent me said to do. Then activated it online. That went smoothly.
I have access to T-Mobile's 5G, so in SCP it says I'm on either B66, B2 or B12. But that's probably b/c I'm in a T-Mobile 5G area.
If I go to an area with only LTE (no T-Mobile 5G), would it then go back to Sprint LTE?