Panasonic Pure IP-PBX KX-TDE600 Installation Manual page 22

1.1.2 Expanded System
2-shelf System
Expanded system (Basic Shelf + 1 Expansion Shelf). Expansion Shelf 1 is mounted on the Basic Shelf.
CAUTION
If you are installing a 2-shelf system in an area prone to earthquakes, make sure to fix the system to the
wall using the wall brackets (supplied with an optional Mounting Kit).
22 Installation Manual Document Version 2009-12