The history of mobile phones covers mobile communication devices that connect wirelessly to the public switched telephone network. While the transmission of speech by signal has a long history, the first devices that were wireless, mobile, and also capable of connecting to the standard telephone network are much more recent. The first such devices were barely portable compared to today's compact hand-held devices, and their use was clumsy. Drastic changes have taken place in both the networking of wireless communication and the prevalence of its use, with smartphones becoming common globally and a growing proportion of Internet access now done via mobile broadband. Foundations Predecessors In 1908, Professor Albert Jahn and the Oakland Transcontinental Aerial Telephone and Power Company claimed to have developed a wireless telephone. They were accused of fraud and the charge was then dropped, but they do not really seem to have proceeded with production. In 1917 the Finnish inventor Eric Tigerstedt successfully filed a patent for a "pocket-size folding telephone with a very thin carbon microphone". Beginning in 1918, the German railroad system tested wireless telephony on military trains between Berlin and Zossen. In 1924 public trials started with telephone connection on trains between Berlin and Hamburg. In 1925 the company was founded to supply train-telephony equipment and, in 1926 telephone service in trains of the Deutsche Reichsbahn and the German mail service on the route between Hamburg and Berlin was approved and offered to first-class travelers. Fiction anticipated the development of real-world mobile telephones. In 1906 the English caricaturist Lewis Baumer published a cartoon in Punch entitled "Forecasts for 1907" in which he showed a man and a woman in London's Hyde Park each separately engaged in gambling and dating on wireless-telegraphy equipment. In 1923 Ilya Ehrenburg casually listed "pocket telephones" among the achievements of contemporary technology in a story in his collection Thirteen Pipes (). In 1926 the artist Karl Arnold drew a visionary cartoon about the use of mobile phones in the street, in the picture "wireless telephony", published in the German satirical magazine Simplicissimus. The Second World War (1939-1945) saw the military use of radio-telephony links. Hand-held radio transceivers have been available since the 1940s. Mobile telephones for automobiles became available from some telephone companies in the 1940s. Early devices were bulky, consumed large amounts of power, and the network supported only a few simultaneous conversations. (Modern cellular networks allow automatic and