Aastra 6757I User Manual page 135

Expansion Module Keys
6. Select from "Key 1" through "Key 36" (M670i)
or
Select from "Key 1" through "Key 60" (M675i)
7. In the "Type" field, select Services.
8. (M675i) In the "Label" field, enter a label to apply to this key.
9. Click Save Settings.
Model 6757i IP Phone User Guide 129