HD Quality During Call

[spyder560]

I noticed recently during a call, my Note 5 displayed 'HD' and voice was amazingly clear. I asked my friend whom I was talking to what phone he was on and he was using an iPhone 5s but we were both on Verizon. HD is pretty amazing, sounds like the person is right in the other room on a LAN line. The ringing sounds different as well. Anyone else experience this?

I talked to my other friend with an iPhone 5s but on ATT and we didn't have the same quality.