Zoom is entirely dependent on whatever hardware the participants are using. My team switched to using cardioid mics and the audio quality is stellar. It's just when you get that one guy dialing in on his mobile phone with an old pair of wired earbuds with the cord mic that's not anywhere near his mouth. Usually from India, with horns in the background...

VoLTE is far superior to 3G calling and deserves its own category here imo. Night and day difference.