For TwInnensechskant intercom systems with intercom traffic, microcomputer-controlled and with headphone locking. It features a high-quality electret microphone, a dynamic ear capsule, and a speaker for call signals. The device includes a magnetic fork switch, optimal operation through illuminated function keys, and a night design. It offers call differentiation for door and floor calls, with 5 melodic ringtone variants that can be selected by the end user. The LED call indicator has a call memory function and a maximum call volume of 90 dBA, with 4 adjustable volume levels. The call button is model 17646, and the pre-wiring is done via a plug-in screw terminal. There is no interruption of the bus line when disassembling the device, and it features a one-person adjustment procedure with programming protection. Additionally, there are 3 slots for additional modules.