For especially ... special people, I think the only solution is with hardware. They need a headset that has a physical toggle switch. Not a button where the mut

For especially ... special people, I think the only solution is with hardware. They need a headset that has a physical toggle switch. Not a button where the mute state is an internal state of some device, but instead a switch (or knob) with two separate physical positions for mute and unmute. This way they are not faced with the mental challenge of tracking the mute state, but have a physical manifestation of it at their fingertips and can develop muscle memory to switch it on and off only for the duration they speak. It also means they can mute without having to alt-tab back to the window of the call (because of course they were checking their email in the meantime). Then the policy is that they cannot join unless they use the headset.