The MuteDeck software checks your computer to see if Zoom is running. If it's running, it scans the user interface to see what buttons are present. I.e., it looks for the Mute button and if it's there, it means you're unmuted. If the Unmute button is there, it means you're on mute.
When MuteDeck detects an active call, it mirrors the buttons with the active status of that feature. When you press unmute on Zoom, it detects this and changes the button inside MuteDeck. When you press mute on MuteDeck, it sends a simulated click to Zoom and detects whether the mute was successful.
Microphone Control as a Fallback
MuteDeck currently supports Zoom detection for all buttons (mute, video, share, leave). If a Zoom call is not found, MuteDeck falls back on the microphone you're using. This means you still have mute control with any conference call software, which is pretty awesome!
If you're curious about how that looks, here's an example from Microsoft Teams: