AASTRA 4422 IP Office (SIP) for MX-ONE User Guide - Manual (Page 101)

101 Dialog 4422 IP Office
Installation
Install key panel (optional)
1 Fasten the connector in the bottom of the hole using a
finger or a blunt tool. Make sure the connector fits before
pressing it down.
2 Press where the arrows are pointing, until you hear a
“Click” sound.
3 Install the stands as shown in the picture in section
“Stand positioning”.
Note: The key panel must be of type DBY 419 01, and it
can only be used in newer versions of the telephone
system.