Bosch Integral TS13 Operating Instructions Manual page 17

You can cancel all operating procedures at any time. You can clear the current
connection in the same way.
Activating functions with function keys
Canceling an operation
Familiarize yourself with your phone
Several functions can also be activated
R
using a function key, e.g. refer-back.
Functions that can be activated using a
function key are not contained in the menu
selection.
Lift the handset.
You can cancel an operation at any time if
you change your mind or inadvertently acti-
vate the wrong function.
The phone returns to the status it had be-
fore the function was selected.
Basic operating rules "
17