AASTRA 4223 Professional for BusinessPhone User Guide - Manual (Page 119)

119 BusinessPhone — Dialog 4223 Professional / Dialog 3213
Installation
Installation
Dialog 4223 Professional
Install cables
You can put the cable to the handset in the notch underneath the
telephone. The cable to the exchange has to be plugged in LINE
and the handset cable has to be plugged in HANDSET.
Change cables
To remove a cable, use a screwdriver to unlock the stop.
Handset cable to the left Handset cable to the right