My s20 updated on 20/12 and the wifi calling has completely disappeared. Went to an o2 shop and was told I'd have to bear with it until a rectifying update comes out
Mine doesn't have those codes but is a UK s20 5g with an O2 monthly contract sim card. Wifi calling is working fine.
I did have a problem a couple of weeks back when it disappeared and the setting was unavailable. After a web search I discovered something that worked for me:
Restart the phone and VERY QUICKLY go to the phone app, settings and the wifi calling setting may be there. Turn it on.
If you are too slow the setting does not show. It took me a couple of goes but it did work.
I have now tried everything on here and still nothing. I did go for the heartache option of factory reset and have spent the day getting most things back working but still no WIFI calling. When you are somewhere with no signal its awful to try and reset and end up worse off. Any other suggestions greatly received.
In the end I had to wait for a new Samsung update. We may have another one soon.
Start the update process and when the phone powers off, take out the Sim card. After the restart, wait for the update to complete, then insert the sim card. WiFi settings returned for me and have survived several restarts.
I guess I'll have to do the same at the next update but once a month is OK.
I just did the latest Samsung update with the Sim card removal process as described in my earlier post.
Worked fine, WiFi Calling returned a few seconds after replacing the Sim.