Aastra Telecom 6757I CT - Manual (Page 144)

134 Model 6757i CT IP Phone User Guide
Line Keys and Softkeys
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 to save your changes.