Might be beneficial just having a word with your Network just to ensure Wi-Fi Calling is definitely still turned On in your account @Beeshive
Check your phone's settings for Wi-Fi Calling.
As a process of elimination can you try your sim card in another phone to see if Wi-Fi Calling works ?
If it is then send some feedback to Samsung via your Samsung Members App.
Daily Driver > Samsung Galaxy s²³ Ultra 512Gb in Phantom Black.The advice I offer is my own and does not represent Samsung’s position. I'm here to help. " This is the way. "