Aastra Telecom 6757I CT - Manual (Page 119)

Model 6757i CT IP Phone User Guide 109
Line Keys and Softkeys
Expansion Module Keys
5. Select from “Key 1” through “Key 36” (M670i)
or
Select from “Key 1” through “Key 60” (M675i)
6. In the "Type" field, select "Flash".
7. (M675i) In the "Label" field, enter a label to display on the phone for the key.
8. Click to save your changes.