The museum opened in 1991 in the courtyard wing of a scheduled historic building, in one of the fine old streets of the Buda Castle District. The building was once a priory, later the seat of Parliament and the King's Court, and then, after alterations, the seat of the Lieutenancy Council. From the end of the 19th century, it housed the Ministry of the Interior. Space was found here in 1928 for a sub-exchange of the Krisztina Telephone Exchange (the first automatic telephone exchange in the country). This continued to operate until 1985. The museum was organized around the Rotary 7A1-type sub-exchange, which is still in working order. It presents, as a living museum, the relics of thelephone history. The exhibits include Tivadar Puskás's first hand-operated, local-battery telephone exchange, with a crossbar switchboard.