what a surprise! bought a 6s+ and transferred my 6 to my wife. Just placed my first call to her today and we were both totally shocked at the sound. super clear audio that was a little disconcerting actually. almost had a tone to it like being in a bathroom. at any rate, it was very noticeable. i had totally forgotten about hd voice. i will say though that the audio broke up a little and at times had a digital feel to it. according to Verizon's FAQ, it's still a new technology that's being improved and one should expect occasional issues. still neat.