The first generation of systems for mobile telephony was analog, circuit switched, and it only carried voice traffic. The analog phones used in 1G were less secure and prone to interference where the signal is weak. Analog systems include AMPS, NMT and ETACS.
The second-generation phones cover all speech into digital code, resulting in a clear signal that can be encrypted for security. Most also include some kind of messaging, as well as support for Centrex style services such as voice mail and caller ID.
The successor of the 2G technology is the 2.5G. 2.5 G supports higher data speeds. The term 2.5G also applies to technology such as WAP (Wireless Application Protocol), which uses a version of the web to fit into a mobile phone’s slow data rate and small screen.
As the use of 2G phones became more widespread and people began to utilize mobile phones in their daily lives, it became clear that demand for data services (such as access to the internet) was growing. Furthermore, experience from fixed broadband services showed there would also be an ever increasing demand for greater data speeds. The 2G technology was nowhere near up to the job, so the industry began to work on the next generation of technology known as 3G.
By 2009, it had become clear that, at some point, 3G networks would be overwhelmed by the growth of bandwidth-intensive applications like streaming media. Consequently, the industry began looking to data-optimized 4th-generation technologies, with the promise of speed improvements up to 10-fold over existing 3G technologies.
5G is not officially used for any specification or official document yet made public by telecommunication companies or standardization bodies such as 3GPP, WiMAX Forum, or ITU-R.