2G (or 2-G) is short for second-generation cellular network. It was commercially launched on the GSM standard in Finland by Radiolinja (now part of Elisa Oyj) in 1991 following the limitation of its predicessors e.g 1G Mobile handsets and their support networks to the spread and increase in mobile communication mass adoption. Mobile technology was evolving to be interoperable (i.e inter-operator and international roaming) and affordable (i.e from mobile handsets to services subsription).
This phenomenal advent of 2G technology was as a result of the cooperative efforts that were pioneered by European countries with the formation and work of:

• R21: As early as 1980, the Telecommunications Commission of CEPT, its Radiocommunications Working Group and its frequency sub-working group R21 managed to have mobile services added at 900 MHz in the International Table of Frequency Allocations, and dedicate a total capacity of 1000 channels (2 x 25 MHz) for new civil mobile use, paving way for the frequency spectrum to be utilized for cellular network;
• GSM: In 1982, the (Groupe Special Mobile by then) working group was formed by the Telecommunications Commission of CEPT to harmonize the technical and operational characteristics of a public mobile communications system in the 900 MHz band;
• ETSI: Established in 1988 to define the standards and technical specification for GSM (Global System for Mobile communications) technology.

GSM became the predominant 2G technology that swept through most parts of the world, and went on to serve 80% of the mobile market in the decades to come. The USA equivalent is IS-54, also known as Digital-AMPS, which was later replaced by IS-136. In cases where the 900 MHz frequency range was used for both 1G and 2G systems in Europe, the 1G systems were shut down to make space for the 2G systems.
In 1992, for the first time, data service was introduced to the mobile network in addition to voice, namely Short Message Service (SMS), which supports a data rate of 9.6kbps. The first SMS was sent by engineer Neil Papworth on December 3rd, 1992 where he typed "Merry Christmas" from a computer to then Vodafone director Richard Jarvis on an Orbitel 901 handset.

The three primary benefits of 2G networks over their predecessors were:

• Digitally encrypted phone conversations, at least between the mobile phone and the cellular base station but not necessarily in the rest of the network.
• Significantly more efficient use of the radio frequency spectrum enabling more users per frequency band.
• Data services for mobile, starting with SMS text messages.

GPRS (General Packet Radio Service) also known as 2.5G that supports packet switching for data rates up to 160 kbps was introduced in 1995, and EDGE (Enhanced Data Rates for GSM Evolution) also known as 2.75G that supports 8PSK modulation for data rates up to 500 kbps was introduced in 1997.
Ericsson became a major manufacturer of 2G network equipment, roughly 40% of 2G calls were made through Ericsson equipment in the 1990s.