The problem started at the time I upgraded my phone to a Pixel 4a. I will suddenly be unable to make or receive phone calls, or texts. It happens every once in a while, with no pattern as to place or time. I've tried turning airplane mode on and off. I've tried turning advanced calling on and off. I've tried resetting the network settings. I tried factory resetting my phone once too. Nothing seems to help. I called customer support and was told that my account plan is deprioritized and to make basic phone calls I need to upgrade my plan. Is this correct?
That makes absolutely zero sense..you definitely got an agent that was a new hire...(or a shady one hoping to con you with a plan upgrade because Verizon is pushing those)
The only thing that can be depriotized is data speed, not voice calls.