The development of cellular phone systems .
1G is the first generation of cellular telephony systems . Signal using modulated analog input channels to communicate by using a frequency into a small box with this method is limited in the number of channels. And utilization Thus impedes the expansion of telephone . And extended frequency band Coinciding with the radio transmitter the size of the cell. And signal strength to reach the base station . The cellular phone also large . The 1G also have problems with channels and devices is large. It also sends information only letter sounds. Later he switched to digital.