vasanjv's Blog

In the 1990s, 'second generation' (2G) mobile phone systems such as GSM, IS-136TDMA"), iDEN and IS-95 ("CDMA") began to be introduced. The first digital cellular phone call was made in the United States in 1990, in 1991 the first GSM network (Radiolinja) opened in Finland. 2-G 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 2-G 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 2-G systems. In America the IS-54 standard was deployed in the same band as AMPS and displaced some of the existing analog channels. ("

Coinciding with the introduction of 2-G systems was a trend away from the larger "brick" phones toward tiny 100–200g hand-held devices, which soon became the norm. This change was possible through technological improvements such as more advanced batteries and more energy-efficient electronics, but also was largely related to the higher density of cellular sites caused by increasing usage levels.