AASTRA 4225 Vision for MX-ONE (TSE) User Guide EN - Manual (Page 120)

Installation
Dialog 4223 Professional/Dialog 4225 Vision 120
Install key panels
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”.
Notes:
All key panels must be of type DBY 419 01.