Aastra 6755i - Mute

150 Model 6755i IP Phone User Guide
Line Keys, Programmable Keys, and Softkeys
Programmable Keys
5. Select from "Key 1" through "Key 6"
6. In the "Type" field, select Empty.
Expansion Module Keys
7. Select from “Key 1” through “Key 36” (M670i)
or
Select from “Key 1” through “Key 60” (M675i)
8. In the "Type" field, select Empty.
9. Click to save your changes.