1G refers to the first generation of wireless telephone technology in mobile telecommunications. The analog telecommunications standards that were introduced in the 1970s and continued until being replaced by 2G digital telecommunications.
In the 1970s, the First Generation, or 1G, mobile networks were introduced. These systems were referred to as cellular, which was later shortened to “cell”, due to the method by which the signals were handed off between towers. Cellular phone signals were based on analog system transmissions, and 1G devices were comparatively less heavy and expensive than prior devices; 0G.
The main difference between the two mobile telephone systems (0G and 1G), is that the radio signals used by 1G networks brought about more faster and reliable technologies than that of 0G. Much-less to that, they were all analogue based.
1G used digital signaling to connect the radio towers with which listen to the handsets to reach to the rest of the telephone system, the voice itself during a call is modulated to higher frequency, typically 150 MHz and up. One such standard is NMT (Nordic Mobile Telephone), used in Nordic countries, Switzerland, Netherlands, Eastern Europe and Russia.
Others include; AMPS (Advanced Mobile Phone System) used in the North America and Australia, TACS (Total Access Communications System) in the United Kingdom, C-450 in West Germany, Portugal and South Africa, Radiocom 2000 in France, and RTMI in Italy.
In Japan there were multiple systems. Three standards, TZ-801, TZ-802, and TZ-803 were developed by NTT (Nippon Telegraph and Telephone Corporation), while a competing system operated by DDI (Daini Denden Planning, Inc.) used the JTACS (Japan Total Access Communications System) standard.
The global mobile phone market during the 0G era, grew from 30 to 50 percent annually with the appearance of the 1G network, and the number of subscribers worldwide reached approximately 20 million by 1990. Prior to 1G technology was the Mobile Radio Telephone also known as 0G.