I just purchased a samsung galaxy and am using the walmart family plan. When I try to use wi fi calling it says not registered....but it won't register. I also can't seem to find any good service even though the map we looked at at the store before we purchased it said we should be fine.
You need to go into your tmobile account online and register your physical address in the 911 section. This will enable wifi calling. I had to do it when I went to a store. Reps couldnt figure it out. Tech support helped me.