For TwInnensechskant door intercoms with intercom traffic, microcomputer controlled and with earphone interlock. It features a high-quality electret microphone, dynamic listening capsule, and loudspeaker for call signals. The device includes a magnetic fork switch, optimum operator guidance by illuminated function keys, and a night design. It offers call differentiation for door calls and storey calls, with 5 melodic call tones selectable by the end user. The LED call display has a call memory function and a maximum call volume of 90 dBA, with 4 adjustable volume levels. The call switch is model 17646, and pre-wiring is done by a pluggable screw terminal. There is no disconnection of the bus line when disassembling the device, and it features a one-man setting procedure with programming protection. Additionally, there are 3 slots for additional modules.