Ericsson DIALOG 4220 - Manual (Page 92)

Installation
Dialog 4220 Lite/Dialog 4222 Office 92
3 Use a screwdriver and press hard in the bottom of the
hole, until you hear a weak sound.
4 Install the stands as shown in picture “Stand
positioning”.
Note: The key panel must be of type DBY 419 01, and it
can only be used in newer versions of the exchange.
Stand positioning