This surface-mounted internal video unit with colour screen comes equipped with a door opener key and a key which can be used to operate one of the following functions: switching the light on/off, calling up camera images or emitting a control function. The device also has a switch on the side to switch the ringtone on and off, as well as a ringtone volume control. In stand-by mode (video off) the image brightness and contrast can be adjusted manually. Parallel connection to another internal video unit is possible The receiver is used to communicate with the visitor.