1.Press "Chk Msg's" MEAN WHAT BUTTON IS THAT ?" means....
"Step 1 - press the button on the phone that has been programmed to dial the calling group assigned to the voicemail"
So on your phones, it is typical to program a button to allow the user to get to the voicemail system by pressing a single button instead of dialing a 3-digit calling group number. The calling group number is typically 770, although I usually use group 777 instead, so it is the same code as on a Partner system (just because I installed Partners and Legend during the same time period). The button might be labeled "Chk Msg's" (Check Messages), "Get Voicemail", "Call Voicemail", "AD-770" or whatever the installer/programmer decided on. I created those cheat sheets so that when I am in the field, I can pull up and print out user guides for my customers, so I did them with my own terminology and how I would label the buttons.
Hope that helps!