Aastra 6755i User Manual page 142

Expansion Module Keys
8. Select from "Key 1" through "Key 36" (M670i)
or
Select from "Key 1" through "Key 60" (M675i)
9. In the "Type" field, select Services.
10. (M675i) In the "Label" field, enter a label to apply to this key.
11. Click
134
to save your changes.
Model 6755i IP Phone User Guide