I used to do big Skype calls in the finance company I worked at several years ago and it was de rigueur to stay on mute until you wanted to talk. Most people actually did it. I always wondered why they didn't just have push to talk as it's way more convenient and less error prone.

I discovered an interesting feature around muting one day as well. People used to conduct calls at their desk in the open office as there was nowhere else to go. It was awful, but worse was if I was in the same call as someone near me as I'd hear them both in my earpiece and across the room. One day it was my boss, sitting right next to me. I noticed that each caller had a mute icon next to them so I pressed his and, lo! It worked. I could no longer hear him in my earpiece. But neither could anyone else. Turns out you could remotely activate any other caller's mute button.