Siemens hicom 150 e - Setting and Programming Your Telephone; Basic Telephone Settings

Answering Calls
37
Setting the Volume
You can change the volume of the handset speaker; in other words,
you can select the volume at which you would like to hear the other
party.
The call display is replaced by the Volume dialog box.
Use the and buttons to adjust the volume at which you
hear the other party in eight steps. Click the Back button in the Vol-
ume box to return to the call display. The value you selected is
stored.
Click the volume button in the toolbar.