Siemens 600Series - Manual (Page 24)

1-10 ROLMphone 300/600 Series User Guide
Keyboard Expansion Option
The keyboard of a ROLMphone 600 series telephone can be expanded
with an option providing 20 additional feature or line keys and status
lights. The Keyboard Expansion Option (KEO) attaches to the right
side of the telephone through a special connector and bracket. Before
the option is installed, the telephone must be configured for it at the
communications server. For more information, see your system
administrator.
Figure 1-9. Keyboard Expansion Option (KEO)