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Mobile telephony is the provision of telephone services to phones which may move around freely rather than stay fixed in one location. Mobile phones connect to a terrestrial cellular network of base stations (cell sites), whereas satellite phones connect to orbiting satellites. Both networks are interconnected to the public switched telephone network (PSTN) to allow any phone in the world to be dialed. In 2010 there were estimated to be five billion mobile cellular subscriptions in the world. == History == According to internal memos, American Telephone & Telegraph discussed developing a wireless phone in 1915, but were afraid that deployment of the technology could undermine its monopoly on wired service in the U.S. Public mobile phone systems were first introduced in the years after the Second World War and made use of technology developed before and during the conflict. The first system opened in St Louis, Missouri, USA in 1946 whilst other countries followed in the succeeding decades. The UK introduced its 'System 1' manual radiotelephone service as the South Lancashire Radiophone Service in 1958.〔(【引用サイトリンク】title=Asset Bank | Image Details )〕 Calls were made via an operator using handsets identical to ordinary phone handsets.〔(【引用サイトリンク】title=Asset Bank | Image Details )〕 The phone itself was a large box located in the boot (trunk) of the vehicle containing valves and other early electronic components. Although an uprated manual service ('System 3') was extended to cover most of the UK, automation did not arrive until 1981 with 'System 4'. Although this non-cellular service, based on German B-Netz technology, was expanded rapidly throughout the UK between 1982 and 1985 and continued in operation for several years before finally closing in Scotland, it was overtaken by the introduction in January 1985 of two cellular systems - the British Telecom/Securicor 'Cellnet' service and the Racal/Millicom/Barclays 'Vodafone' (from voice + data + phone) service. These cellular systems were based on US Advanced Mobile Phone Service (AMPS) technology, the modified technology being named Total Access Communication System (TACS). In 1947 Bell Labs was the first to propose a cellular radio telephone network. The primary innovation was the development of a network of small overlapping cell sites supported by a call switching infrastructure that tracks users as they move through a network and passes their calls from one site to another without dropping the connection. In 1956 the MTA system was launched in Sweden. The early efforts to develop mobile telephony faced two significant challenges: allowing a great number of callers to use the comparatively few available frequencies simultaneously and allowing users to seamlessly move from one area to another without having their calls dropped. Both problems were solved by Bell Labs employee Amos Joel who, in 1970 applied for a patent for a mobile communications system.〔Patent No. 3,663,762, issued May 16, 1972.〕 However, a business consulting firm calculated the entire U.S. market for mobile telephones at 100,000 units and the entire worldwide market at no more than 200,000 units based on the ready availability of pay telephones and the high cost of constructing cell towers. As a consequence, Bell Labs concluded that the invention was "of little or no consequence," leading it not to attempt to commercialize the invention. The invention earned Joel induction into the National Inventors Hall of Fame in 2008.〔List of National Inventors Hall of Fame inductees〕 The first call on a handheld mobile phone was made on April 3, 1973 by Martin Cooper, then of Motorola〔(【引用サイトリンク】title=30th Anniversary of First Wireless Cell Phone Call )〕 to his opposite number in Bell Labs who were also racing to be first. Bell Labs went on to install the first trial cellular network in Chicago in 1978. This trial system was licensed by the FCC to ATT for commercial use in 1982 and, as part of the divestiture arrangements for the breakup of ATT, the AMPS technology was distributed to local telcos. The first commercial system opened in Chicago in October 1983.〔Article by Larry Kahaner and Alan Green in the Chicago Tribune of December 22, 1983 (Reach out and touch someone--by land, sea or air )〕 A system designed by Motorola also operated in the Washington D.C./Baltimore area from summer 1982 and became a full public service later the following year.〔Visited and evaluated by a group of (soon-to-be) British Telecoms staff (including writer) in September 1982.〕 Japan's first commercial radiotelephony service was launched by NTT in 1978. The first fully automatic first generation cellular system was the Nordic Mobile Telephone (NMT) system, simultaneously launched in 1981 in Denmark, Finland, Norway and Sweden.〔(【引用サイトリンク】title=Swedish National Museum of Science and Technology )〕 NMT was the first mobile phone network featuring international roaming. The Swedish electrical engineer Östen Mäkitalo started to work on this vision in 1966, and is considered as the father of the NMT system and some consider him also the father of the cellular phone.〔(【引用サイトリンク】title=Mobile and technology: The Basics of Mobile Phones )〕〔(【引用サイトリンク】title=Facts about the Mobile )〕 The advent of cellular technology encouraged European countries to co-operate in the development of a pan-European cellular technology to rival those of the US and Japan. This resulted in the GSM system, the initials originally from the ''Groupe Spécial Mobile'' that was charged with the specification and development tasks but latterly as the 'Global System for Mobile Communications'. The GSM standard eventually spread outside Europe and is now the most widely used cellular technology in the world and the de facto standard. The industry association, the GSMA, now represents 219 countries and nearly 800 mobile network operators.〔(【引用サイトリンク】title=Full Members ~ GSM World )〕 There are now estimated to be over 5 billion phone subscriptions according to the "List of countries by number of mobile phones in use" (although some users have multiple subscriptions, or inactive subscriptions), which also makes the mobile phone the most widely spread technology and the most common electronic device in the world.〔(global cellphone penetration reaches 50 percent )〕 The first mobile phone to enable internet connectivity and wireless email, the Nokia Communicator, was released in 1996, creating a new category of multi-use devices called smartphones. In 1999 the first mobile internet service was launched by NTT DoCoMo in Japan under the i-Mode service. By 2007 over 798 million people around the world accessed the internet or equivalent mobile internet services such as WAP and i-Mode at least occasionally using a mobile phone rather than a personal computer. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Mobile telephony」の詳細全文を読む スポンサード リンク
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