Call waiting with “Caller ID” uses a special signal in
order to warn you about an incoming call, during another call there are shown the
name and number of the calling subscriber on the display. The function also
allows switching between two calls.
The program asking you to enter the extension number of the person or department you are trying to reach. When the caller enters an extension number, the system asks the name of the caller in order to inform the called party about an incoming call, presenting the caller.