With functions for calls, voice, door opening, lighting, and floor calls. Hearing protection and privacy features are integrated. The call mute function has a status indicator. It allows for a parallel connection of up to 4 bus phones as standard (from the 3rd device, the PRI 602-... USB and ZBVG 650-... are required for programming). There is call differentiation for floor calls, 2 door calls, and internal calls. A door opener button is included, and the light and call mute buttons are freely configurable and can be double-assigned. The call generator offers 11 ringtone sequences, including a gong. The volume can be adjusted in 5 levels up to a maximum of 83 dB(A). The door opening and lighting functions can be activated at any time via bus lines, and door opening is always possible. An accessory connection relay ZAR 850-... can be retrofitted to connect an additional signaling device. The base plate with connection terminals can be pre-installed. It can also be used as a tabletop device with the table accessory ZTS 800-....