Siemens 600Series - Manual (Page 31)

Introduction 1-17
1.
Int
roduc
tion
Voice Volume Keys
Use the Volume Up (▲) and Volume Down (▼) keys to adjust the
voice volume of your telephone. While on a call, press ▲ to raise the
volume of the voice you are hearing, or press ▼ to lower the volume
of the voice you are hearing. Press either key until you reach the
desired voice level. When you hang up or switch to another call, the
voice volume returns to the default level.