Meeting hosts and their attendees can use phone keypad commands (DTMF controls) during a meeting or audio conference.  You'll find a handy wallet card template attached here where you can find these commands and enter your bridge information.  The following commands are available from your phone keypad during a audio conference:

*1 = Menu (All)
*2 = Caller count (Host Only)
*5 = Mute All/ Unmute All (Host Only)
*6 = Mute/ Unmute myself (All)
*7 = Lock/Unlock Conference (Host Only)
*8 = Entry/Exit Chimes (Host Only)