Using the telephone : Getting to know your telephone : Volume keys
Volume keys
Set volume for receiver/headset, ringtone, handsfree mode and indicating appointments:    Press the volume keys / on the right side of the handset
Display keys
The display keys perform a range of functions depending on the operating situation.
 Display key icons
 
The display keys have a function preset by default in idle status.
Changing the assignment  Assigning display keys, changing assignments