Audio set Siedle Compact in 1+n technology with the functions of call, voice transmission, and door opener. Number of integrated call buttons: 1. Each Compact set can be expanded with an additional indoor station per call button and supplemented with a secondary signaling device. Included in the delivery are the Siedle Compact audio door station (brushed stainless steel), a standard indoor telephone, a transformer, and an integrated door speaker. The voice volume is adjustable. Available number of integrated call buttons: 1 (CA 812-1), 2 (CA 812-2), 4 (CA 812-4). The illuminated nameplates can be changed from the front, and there is an illuminated information sign for house numbers, logos, opening hours, etc. Designed for surface mounting with a brushed stainless steel frame. The functions of the indoor station HTS 811-0 include a door call as a 3-tone call and a floor call as a 2-tone call, possible in the Compact set with Zert 811-0. Integrated call muting is available via the volume control, and the call volume can be continuously adjusted from outside via the volume control up to a maximum of 83 dB(A).