Getting URGENT emails to upgrade my 5G phone rgdg 3G retirement. WHY?

as long as it works with TMOs VoLTE you should be fine. calls and texts pretty much go over 3G so if it doesnt work then you wont be able to make/receive calls and possibly texts.

if VoLTE is turned on right now and you make a call you should see something at the top in the notifications area showing you are connected to VoLTE..it’ll either say it or there will be a phone symbol with VoLTE right above it..if those are not there then the devices VoLTE might not be compatible with the TMO set up.

also a problem you might run into.

was it purchased from TMO or brought in from elsewhere?