Hi @SpanishinLondon
welcome to Three users community.
So you have data, but you cannot do or receive voice calls and SMS, is that it?
wifi calls is slightly different from using whatsapp or other similar app to do calls. Wifi calling kind means your phone can use the wifi network/broadband to make and receive calls, when network signal or coverage isn't great. Example: if your phone is caple of wifi calling and such option is active and your phone is "registered" or swithched to wifi calling (again depends on the signal strength), you will see, on a incoming or outgoing call, the wifi symbol or "wifi" or "wifi calling" on the screen.
just to add, that on wifi calling you will be charged as normal call, whilst using whatsapp or signal or whatever it is just data (KB or MB) usage
