If you have the LS777 (
LG Stylus 3 - Full phone specifications) then you are out of luck. As far as I can tell, it does not have VoLTE, which means T-Mobile is out of the question since you cant use GSM to place calls and would be at the mercy of the very limited 3G coverage (should still be able to text/use data). Verizon, while compatible, will shutdown CDMA at the end of 2022, so even if you try to get it activated (odds are you wont be able to, they haven't accepted CDMA phones for a while) it will only work until 2023 due to the same lack of VoLTE. And finally, ATT. There, you should be able to place calls over 3G, but guess what, they are shutting down 3G in February. So yeah, I would be trying to force a new phone out of boost if I were you.