Siedle Basic video set in bus technology with the functions calling, speaking, viewing and door opening., Number of call buttons: 1, Each basic set can be expanded to include selected door and indoor stations as well as switching functions and a telephony connection. , Scope of delivery:, . Siedle Basic video door station (CV 850-1-. E), . Siedle Basic video indoor station (VIB 150-.), . Set power supply unit (SNG 850-.)