Editing Digital AMPS (section)

==History==
The evolution of [[mobile communication]] began in three different geographic regions: [[North America]], [[Europe]] and [[Japan]]. The standards used in these regions were quite independent of each other.{{cn|date=April 2017}} 

The earliest mobile or wireless technologies implemented were wholly analogue, and are collectively known as 1st Generation ([[1G]]) technologies. In Japan, the 1G standards were: [[Nippon Telegraph and Telephone]] (NTT) and the high capacity version of it ([[Hicap]]). The early systems used throughout Europe were not compatible to each other, meaning the later idea of a common 'European Union' viewpoint/technological standard was absent at this time.{{cn|date=April 2017}} 

The various 1G standards in use in Europe included [[C-Netz]] (in Germany and Austria), Comviq (in Sweden), [[Nordic Mobile Telephone]]s/450 (NMT450) and NMT900 (both in Nordic countries), NMT-F (French version of NMT900), TMA-450 (Spanish version of NMT450), Radiocom 2000 (RC2000) (in France), [[Total Access Communication System|TACS]] (Total Access Communication System) (in the [[United Kingdom]], [[Italy]] and [[Republic of Ireland|Ireland]]), and TMA-900 (Spanish version of TACS). North American standards were [[Advanced Mobile Phone System]] (AMPS) and Narrow-band AMPS (N-AMPS).

Despite the [[Nordic countries]]' cooperation, European engineering efforts were divided among the various standards, and the Japanese standards did not get much attention{{by whom|date=April 2017}}. Developed by [[Bell Labs]] in the 1970s and first used commercially in the [[United States]] in 1983, AMPS operates in the 800 [[MHz]] band in the United States and is the most widely distributed analog cellular standard. (The 1900 [[MHz]] [[Personal Communications Service|PCS]] band, established in 1994, is for digital operation only.) The success of AMPS kick-started the mobile age in the North America.

The market showed an increasing demand because it had higher capacity and mobility than the then-existing mobile communication standards were capable of handling. For example, the Bell Labs system in the 1970s could carry only 12 calls at a time throughout all of [[New York City]]. AMPS used [[Frequency Division Multiple Access]] (FDMA) which enabled each cell site to transmit on different frequencies, allowing many cell sites to be built near each other.

AMPS also had many disadvantages, as well. Primarily, it did not have the ability to support the ever-increasing demand for mobile communication usage. Each cell site did not have much capacity for carrying higher numbers of calls. AMPS also had a poor security system which allowed people to steal a phone's serial code to use for making illegal calls. All of these triggered the search for a more capable system.

The quest resulted in '''IS-54''', the first American 2G standard. In March 1990, the North American cellular network incorporated the IS-54B standard, the first North American dual mode digital cellular standard. This standard won over [[Motorola]]'s Narrowband AMPS or N-AMPS, an analog scheme which increased capacity, by cutting down voice channels from 30&nbsp;kHz to 10&nbsp;kHz. IS-54, on the other hand, increased capacity by digital means using [[time-division multiple access|TDMA]] protocols. This method separates calls by time, placing parts of individual conversations on the same frequency, one after the next. TDMA tripled call capacity.

Using IS-54, a cellular carrier could convert any of its system's [[analogue electronics|analog]] voice channels to [[Digital data|digital]]. A dual mode phone uses digital channels where available, and defaults to regular AMPS where they are not. IS-54 was [[backward compatible]] with analogue cellular and indeed co-existed on the same radio channels as AMPS. No analogue customers were left behind; they simply could not access IS-54's new features. IS-54 also supported [[authentication]], a help in preventing fraud.