<P> In the 1990s , the ' second generation ' mobile phone systems emerged . Two systems competed for supremacy in the global market : the European developed GSM standard and the U.S. developed CDMA standard . These differed from the previous generation by using digital instead of analog transmission , and also fast out - of - band phone - to - network signaling . The rise in mobile phone usage as a result of 2G was explosive and this era also saw the advent of prepaid mobile phones . </P>
<P> In the 1990s , the ' second generation ' mobile phone systems emerged . Two systems competed for supremacy in the global market : the European developed GSM standard and the U.S. developed CDMA standard . These differed from the previous generation by using digital instead of analog transmission , and also fast out - of - band phone - to - network signaling . The rise in mobile phone usage as a result of 2G was explosive and this era also saw the advent of prepaid mobile phones . </P>
when did cell phones become common in the us
when did cell phones become common in the us
the 1990s
the 1990s