Table telephone apparatus Ericsson, Deckert & Homolka, Prague, 1905

Most of the oldest telephone sets were supplied by the firms Siemens & Halske, Czeija & Nissl and Deckert & Homolka that had their subsidiaries in Vienna. The latter of them established soon its subsidiary in Prague. After the World War I, domestic industry started its development in Czechoslovakia that was represented by the firms Telegrafia, Brothers Knotek (Mikrofona), Brothers Prchal and Telektra. Later, due to the inflow of foreign capital, subsidiaries of firms were established, in some cases by transformation of domestic enterprises. These were, in particular, Siemens &Halske (Elektrotechna), Ericsson and Standard Electric. After the World War II, the natinal enterprise Tesla was founded as a result of general nationalization.