Audio set Siedle Basic in bus technology with the functions of calling, speaking, and door opening. Number of call buttons: 1. Each Basic set can be expanded with selected door and indoor stations, as well as supplemented with switching functions and a telephony connection. Delivery includes: Audio door station Siedle Compact CA 850-1, audio indoor station Siedle Basic AIB 150, set power supply SNG 850, SET CAB 850-1 EW.