Mobile telephone networks started with analog technology. Analog cellular networks were known as first generation (1G) networks. Such networks had limited capacity, and were subject to fraud and eavesdropping. Digital cellular telephone networks are known as second generation or 2G networks. Digital cellular networks can support a greater number of users withing a given bandwidth and are much more secure in terms of both eavesdropping and fraud.
The underlying technologies for digital cellular wireless networks are Time Division Multiple Access (TDMA) and Code Division Multiple Access (CDMA). The basic architecture of the network is the same as the 1G analog networks.