Processor-controlled handsfree talking for optimal voice quality even in ambient noise. Audio privacy lock. Safe operation via illuminated and easily recognizable key symbols. Key for accepting and ending a call. Call differentiation (door call/floor call). Five melodic ring tones. Volume of voice playback can be set in several stages. Call silencer with status display. Call volume adjustable in four stages. Only 23 mm height. Door release switch box, flush-mounted or table-mounted. Ten memories for different bell buttons. Robust housing. For surface mounting. Expandable with outdoor unit. Colour: white. Mounting type (indoor): surface-mounted. Intercom system type: door intercom system. Intercom system component: indoor unit. Transmission type: cable.