These are two seperate buttons.
The 'call-appr' is your system intercom (extension number) button. Generally you will have three of these. They are the buttons you make and receive calls on.
The Auto Dial button is a speed dial button.
Both types need to be programmed on your phone by your system administrator.
In the case of the AD button, it is associated with a personal, group or system speed dial list. Once the button is programmed (and associated to a personal list), the user is then able to program the speed dial number using the feature code or an AD program button.
franke