Wouldn’t this be more secure than hoping you are connected to a legitimate tower instead of a stingray, ISMI catcher or the like?
I think most phones can turn off cellular and turn on WIFI. You do need the wifi calling though to use it. It allows calls and texts both ways. It works fine for some of the big carriers with the popular device brrands.
Hopefully the L5 or L6 can get this soon.