Hi Janice. You’re most welcome. Once you have enabled VoLTE, you are good to go. Your phone will still be usable after the 3G shutdown, as it does support 4G.
Thanks so much for this. Got VolTE sorted now. But does that mean I will be able to use 4G, or might my phone still be only 3G compatible and therefore obsolete? It's a Xiaomi Redmi 9T.