Imagine my shock when my cellphone provider Ting emailed me warning that all the four US carriers are shutting down their voice networks in favor of VoLTE (Voice over LTE). The email said that my phone Xiaomi Mi 9T does not have VoLTE capability and so I should switch to a phone that does. This meant that I will not be able to make or receive voice calls soon.
It turns out that my phone does have VoLTE capability. Here is how to enable it: