I'm ashamed to say that it was only today that I've actually experience the call quality through VoLTE when I called my Dad. I have been extensively using Teams or Viber to call people in recent months and the only time I had to make a mobile call, they're mostly people who presumably didn't have VoLTE yet. Anyway, I noticed immediately that the call was different. Starting with how quick the call came through. 2nd, the ringback. It wasn't the typical Globe ringback of "ring-ring, ring-ring". Rather, it was like you're calling a Smart number... the ringback was like a series of long tones. And when my Dad answered, you could hear a significant increase in sound quality. Anyway, I'm using an old Galaxy S8+ while my Dad has a new Galaxy S20.