1G

                                        First Generation wireless technology

First Generation wireless technology (1G) is the original analog, voice-only cellular telephone standard, developed in the 1980s. One such standard is NMT (Nordic Mobile Telephone), used in Nordic countries, Eastern Europe and Russia. Others include AMPS (Advanced Mobile Phone System) used in the United States, TACS (Total Access Communications System) in the United Kingdom, JTAGS in Japan, C-Netz in West Germany, Radiocom 2000 in France, and RTMI in Italy. Analog cellular service is being phased out in most places worldwid.

                                                         Second Generation  wireless technology

The second generation of mobile telephony systems uses digital encoding. 2G networks support high bit rate voice, limited data communications and different levels of encryption. 2G networks include GSM, D-AMPS (TDMA) and CDMA. 2G networks can support SMS applications.

2.5G extends 2G systems, adding features such as packet-switched connection and enhanced data rates. 2.5G networks include EDGE and GPRS. These networks support WAP, MMS, SMS mobile games, and search and directory.

Enhanced Data GSM Environment (EDGE)

A 2.5G technology that enhances GSM. EDGE increases transmission speeds on GSM networks and enables the transmission of large amounts of data at 384Kbps. With EDGE, mobile operators can deliver multimedia and other broadband applications to mobile phones. 

General Packet Radio Service (GPRS)

GPRS is a radio technology for GSM networks that adds packet-switching protocols. As a 2.5G technology, GPRS enables high-speed wireless Internet and other data communications. GPRS networks can deliver SMS, MMS, email, games and WAP applications. 

GSM (Global System for Mobile communications)

GSM, a 2G technology, is the de facto European standard for digital cellular telephone service, and it is also available in the Americas. GSM is the most widely used of the three digital wireless telephone technologies (TDMA, GSM and CDMA), and it supports voice, data, text messaging and cross-border roaming. The SIM (Subscriber Identification Module), a removable plastic card that contains a users data, is an essential element in a GSM network.

GSM operates in multiple frequency bands, GSM 900, GSM 1800, GSM 1900. When GSM is working on a radio frequency of 1800 MHz, it is sometimes referred to as DCS 1800, GSM1800 or PCN. 

Time Division Multiple Access (TDMA)

A technology used in digital cellular telephone communication to divide each cellular channel into three time slots in order to increase the amount of data that can be carried. GSM and D-AMPS use TDMA in one form or another.

TDMA is also known as IS-136. It is also generally used to describe what was formerly known as D-AMPS. TDMA networks are operated in the United States, Latin America, New Zealand, parts of Russia and Asia Pacific.

Multimedia Messaging Service (MMS)

MMS allows for non-real-time transmission of various kinds of multimedia contents, such as images, audio, and video clips.

Messaging

SMS (Short Message Service) is a feature available with some wireless phones that allows users to send and/or receive short alphanumeric messages.
Picture Messaging allows users to send and receive picture messages along with text. Users can choose from several preset and/or received pictures stored in their phones. Some phones also contain a picture editor.
Chat Messaging lets users "talk" using SMS messages.