Aastra DBC 422 Installation Instructions Manual page 92

I DBY 419 01
NSTALLATION OF EXTRA KEY PANEL
Figure 72:Attaching the DBY 419 01 key panel unit to the phone
Mount the proper quantity of feet in recommended positions, 73 Feet
positions with 1 to 4 pcs DBY 419 01 connected (rear view) on page 93.
1531-DBC 422 02 Uen B3 2013-12-02 92