When a trunk call is put on mute and taken off mute the system sends a tone that the caller hears. Any ideas how to turn this off?

Resurrecting this because I was searching the forums and was wondering the same thing. My keyset does not do this, but I have at least 1 user whose does, and he is ALL WOUND UP about it.

The only thing that comes to mind is the system flag Disable Mute Confirmation Tone. It is enabled by default and can't be changed per station, but it's a place to start.