I have a Galaxy S20 Ultra, on AT&T. Wifi calling worked for over a year. Now it stopped working. I go to Settings -> Connections, toggle on WiFi Calling. It tries to enable, but gives me an error. I factory reset and same. I went to AT&T store, they replaced the SIM and it still won't work. I tried going into airplane mode, enable wifi, toggle wifi calling on and it still won't work. I'm fed up!!! Nothing is working to fix it. Why would it work for over a year then die? Oh, I also replaced my xfinity router/modem device for my internet as well and that didn't fix it. Internet wifi works and connects just fine. Ideas??? Help!!!! Thank you.
Mine was also working fine on WiFi calling, now the option for wifi calling has disappeared! What the heck!
Have tried restarting, removing SIM and restarting the adding SIM again - no luck! I am on Ting.
My issue couldn't be resolved. The resolution was for my smartphone hardware to be replaced. Once they gave me a new phone then magically the Wi-Fi calling started working just fine. So frustrating! But, glad that it's working again as this is the only way to do calls from my house due to signal issues here. Good luck with resolving your problem! I wish you well.