Visitors are shown an interactive display in ten different rooms over two floors detailing the development of telephony and the telegraph in Germany. This is the most comprehensive collection of its kind and in 1994 it achieved huge renown by being entered in the Guinness Book of Records. Since then, the collection has grown to over 1,200 devices from two centuries, including a chemical telegraph from 1809. The freely accessible devices document the history of electrical communication from its early days to the present time. Visitors are encouraged to touch, feel and use, but also to dwell on what they are seeing. The museum is particularly proud of the combination of telephonic equipment with contemporary switchboard equipment; many of the exhibits are in working order and are connected to this switchboard. An additional film room invites you to relax and watch the entire development history of telecommunication.