Neither me or my grandma are able to use wifi calling.

We bought our phones from cricket very recently and gave been having this problem from the start. They are cricket phones, with cricket SIM cards, etc. Not once has WiFi calling worked. I have researched this and called support and no solution was found. I've tried everything I can. I've checked and our phones are on the supported devices list. Wifi isn't an issue. It works fine. Wifi calling and texting used to work fine when we used Verizon. We live somewhere without good cell service so my grandma can't use her phone to call anyone when she's home.