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NMT (''Nordisk MobilTelefoni'' or ''Nordiska MobilTelefoni-gruppen'', ''Nordic Mobile Telephony'' in English) is the first fully automatic cellular phone system. It was specified by Nordic telecommunications administrations (PTTs) and opened for service in 1 October 1981 as a response to the increasing congestion and heavy requirements of the manual mobile phone networks: ARP (150 MHz) in Finland, MTD (450 MHz) in Sweden and Denmark, and OLT in Norway. NMT is based on analog technology (first generation or 1G) and two variants exist: NMT-450 and NMT-900. The numbers indicate the frequency bands used. NMT-900 was introduced in 1986 and carries more channels than the older NMT-450 network. The NMT specifications were free and open, allowing many companies to produce NMT hardware and pushing prices down. The success of NMT was important to Nokia (then Mobira) and Ericsson. First Danish implementers were Storno (then owned by General Electric, later taken over by Motorola) and AP (later taken over by Philips). Initial NMT phones were designed to mount in the trunk of a car, with a keyboard/display unit at the driver's seat. "Portable" versions existed, though they were still bulky, and with battery life still being a big problem. Later models such as Benefon's were as small as and weighed only about 100 grams. == History == The NMT network was opened in Sweden and Norway in 1981, and in Denmark and Finland in 1982. Iceland joined in 1986. However, the first commercial service was introduced in Saudi Arabia on 1 September 1981 to 1,200 users, one month before Sweden. By 1985 the network had grown to 110,000 subscribers in Scandinavia and Finland, 63,300 in Norway alone, which made it the world's largest mobile network at the time. The NMT network has mainly been used in the Nordic countries, Baltic countries, Switzerland, Netherlands, Hungary, Poland, Bulgaria, Romania, Czech Republic, Slovakia, Slovenia, Serbia, Turkey, Croatia, Bosnia, Russia, Ukraine and in Asia. The introduction of digital mobile networks such as GSM has reduced the popularity of NMT and the Nordic countries have suspended their NMT networks. In Estonia NMT network was shut down in December 2000. In Finland TeliaSonera's NMT network was suspended on 31 December 2002. Norway's last NMT network was suspended on 31 December 2004. Sweden's TeliaSonera NMT network was suspended on 31 December 2007. The NMT network (450 MHz) however has one big advantage over GSM which is the range; this advantage is valuable in big but sparsely populated countries such as Iceland. In Iceland, the GSM network reaches 98% of the country's population but only a small proportion of its land area. The NMT system however reaches most of the country and a lot of the surrounding waters, thus the network was popular with fishermen and those traveling in the interior. In Iceland NMT service was stopped on 1 September 2010, when Síminn closed down its NMT network. In Denmark, Norway and Sweden the NMT-450 frequencies has been auctioned off to Swedish Nordisk Mobiltelefon which later became Ice.net and renamed to [Nordisk_Mobiltelefon_(Sweden)|[Net 1]] that built a digital network using CDMA 450. During 2015, the network has been migrated to 4G. The permission for TeliaSonera to continue operation of NMT-450 ended on 31 December 2007. In Russia Uralwestcom shut down their NMT network on 1 September 2006 and Sibirtelecom on 10 January 2008. Skylink, subsidiary company of TELE2 Russia operates NMT-450 network as of 2015 in Arkhangelsk region and Perm region. These networks are used in sparsely populated areas with long distance. shut down networks is planned in 2016, but the tailor all off will be rescheduled at a later date 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「Nordic Mobile Telephone」の詳細全文を読む スポンサード リンク
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