2G Mobile

In the 1990s, 'second generation' (2G) mobile phone systems such as GSM, IS-136 ("TDMA"), iDEN and IS-95 ("CDMA") began to be introduced. In 1991 the first GSM network (Radiolinja) opened in Finland. 2G phone systems were characterized by digital circuit switched transmission and the introduction of advanced and fast phone to network signaling. In general the frequencies used by 2G systems in Europe were higher though with some overlap, for example the 900 MHz frequency range was used for both 1G and 2G systems in Europe and so such 1G systems were rapidly closed down to make space for 2G systems. In America the IS-54 standard was deployed in the same band as AMPS and displaced some of the existing analog channels. >>>>