In my area (West Virginia) which is controlled by a Sprint Affiliate (Shentel) we actually have VoLTE on our phones. And the Apple watches even work as a stand-alone when making calls. It’s not exactly immediate when not connected to the phone but I’ve tested it by turning the phone off and it works. I am actually a Sprint rep for an indirect affiliate (VisionMobile). I just ordered a Galaxy Watch and am getting it tomorrow so I look forward to testing it! Would anyone be interested in knowing if it works?