What is GSM?
GSM, the Global System for Mobile Communications, is an open, non proprietary digital cellular system which has rapidly gain worldwide acceptance and market share. In addition to digital transmission, GSM incorporates many advanced series and features, including ISDN compatibility, and worldwide seamless roaming in other GSM networks. The advanced services and architecture of GSM have made it a model for future 3G cellular systems such as UMTS.

About the Technology
GSM uses digital technology and time division multiple access transmission methods
GSM is the basis of powerful family of the platforms for the future- providing a direct link into next generation solutions including GPRS, EDGE and 3GSM.
In GSM, Voice is digitally encoded via a unique encoder, which emulates the characteristics of human speech. This method of transmission permits a very efficient data rate/information content ratio.
GSM has been a system designed with stringent levels of inbuilt security. With constantly enhanced transmission protocols and algorithms added to the flexible and future proof platform, GSM remains the most secure public wireless standard in the world.
GSM Association, based in Dublin, Ireland and London, UK, represents the interests of more than 690 GSM, satellite and 3GSM operators, key manufacturers and suppliers to the GSM industry as well as regulatory and administrative bodies from more than 190 countries and regions around the world.
GSM Association is responsible for the continued maintenance of open standards and interoperability. The global cooperation between operators is most powerfully illuminated by the success of international roaming. One of the Association's major priorities is the development and promotion of the GSM standard worldwide.