Iwatsu ICON Series IX-5910 Owner's Manual page 115

To change the name of a key on the display:
Press and hold (five seconds) the key that corresponds to the label you
want to change.
When the Label Name Change screen appears, use the dial pad and the
navigation keys to enter the new name for the key.
Press Save to save your changes or Cancel to exit the name change
without saving.
Note: Characters advance automatically when changing keys. Advance
manually for the same key.
Return a key label to its default name:
If you have changed the name of the key and wish to return the key name to
its default setting:
Press and hold (five seconds) the desired key that corresponds to the
label you want to return to the default name.
Delete the key name and press Save without entering a new name.
The default key label is now displayed.
IP TELEPHONE USER GUIDE - 95