- First Generation was introduced where network signals were analogue and used Frequency Division Multiple Access (FDMA).
- Second Generation was launched in 1992 in which signals and speech channels were digitally encrypted. 2G used Time Division Multiple Access (TDMA).
- Third Generation has very different functions like it allows simultaneous use of speech and data services at higher rates and better spectral efficiency.
- Constitute of 4G has not been standardized yet. It is non-backward compatible with new higher frequencies bands. It is defined to be comprehensive and secure for the users. 4G will only be packet- based (all-IP) switched network. Facilities like IP-telephony (IP-based voice data), Ultra- broadband internet Access 1GBps (Gigabit speed) Support for IPV6 protocol, Gaming Services, High Definition HDTV, Streamed Multimedia and many more new services are added!!! UMTS operates on frequencies of 850/900/1700/1900/2100 MHz. Most 3G phones support at least 2 frequencies. No 3G phone available which supports all 3G frequencies. It depends on service provider what speed and frequency it adopts for its 3G network and what type of 3G compatible phone you have to fully exploit, utilize and enjoy the services.