Idisagree. It's not up to the carriers..nope.It's a function of your carrier not the OS. Verizon supports V0LTE on the 6P (you have to enabled HD Voice), AT&T doesn't. I don't think either of those support WiFI calling, at least not on non-carrier branded phones. Project Fi will give you both if you can live with the coverage limitations of Sprint/T-Mobile.