...
Extension. Enter a unique number for this extension. For information about the extension-number length, see Extension Settings.
Play Sound on Entry/Exit. Select YES if you want a sound to play as callers enter and exit the conference.
Play Music On Hold for One Person. Select YES if you want Music On Hold to play when there is only one person in the conference.
Press # to be sent to extension. The extension number to transfer calls to when a caller presses # in a conference.
...