AASTRA 4425 IP Vision for BusinessPhone User Guide - Manual (Page 107)

107 BusinessPhone – Dialog 4425 IP Vision
Accessories
Headset (optional)
How to install the headset, see section “Installation ” on page 133.
You can set your IP telephone to headset preset mode. This way
you can make calls without lifting the handset.
Activate headset preset mode
When the headset preset mode is turned off: Í
Press and hold the Headset key for 4 seconds.
Now the Headset preset mode is activated (headset symbol is
shown in the display). All calls can be handled via the headset.
Deactivate headset preset mode
When the headset preset mode is turned on: Â
Press and hold the Loudspeaker key for 4 seconds.
The Headset preset mode is deactivated.