Aastra 9143i Series Administrator's Manual page 26

IP Phone Administrator Guide
IP Phone Models
The M670i module adds 36 additional softkeys to the IP phone models 6753i,
6755i, 6757i, and 6757i CT. The M670i provides paper labels for each softkey. Up
to 3 modules can be piggy-backed to provide up to 108 additional softkeys for the
phone.
The M675i module adds 60 additional softkeys to the IP phone models 6755i,
6757i, and 6757i CT (using the 3 function keys on the bottom right of the unit).
The M675i module provides an LCD display for display softkey labels. Up to 3
modules can be piggy-backed to provide up to 180 additional softkeys for the
phone.
Reference
For more information about installing and using the expansion modules, see your
phone-specific Installation Guide and phone-specific User Guide.
1-6 41-001160-03 Rev 00, Release 2.5