doesnt matter what U will try to do it wont work until U not activate with Your network carier . if Your device is unlocked - sim card is providing info to the system and thats why U cant set the wi fi calling . activate Your wi fi caling option with Your network sim carier and then U gonna find option in a settings. hope thats helps . cheers
I have the same issue with O2. I've contacted O2 and they say it's on my profile their end and to contact Samsung. So I contact Samsung and they say it's O2. Exactly the same, there is no option anywhere to now activate wifi calling on the Samsung S20 5G handset.