GSM IS NOT AN EUROPEAN STANDARD ONLY BUT ALSO OPERATIONAL OVER MORE THAN EIGHTY COUNTRIES AROUND THE WORLD.

In the beginning of cellular systems,each country developed its own system,which was an undesirable situation for the following reasons: The equipment was limited to operate only with in the boundaries of each country. The market for each mobile equipment was limited. In order to overcome these problems, the conference of the European posts and telecommunications formed ,in 1982 .The Group Special mobile (GSM) in order to develop a pan -European Mobile cellular radio system the GSM acronym became later the acronym for Global system for Mobile communications .The standardised system had to meet certain criteria:- Spectrum efficiency, International roaming,Low mobile and base stations costs ,Good subjective voice quality, Compatibility with other systems such as ISDN (Integrated services Digital Net Work) and Ability to support new services . Unlike the cellular systems,which were developed using an analog technology, the GSM system was developed using a digital technology.The reasons for this choice are explained separately.In 1989the responsibility for the GSM specifications passed from the CEPT to the European telecommunication standard institute (ETSI) .The aim of the GSM specifications is to describe the functionality, and the interface for each component of the system, and to provide the guidance on the system.These specifications will then standardise the system in order to guarantee the proper interworking between the different elements of the GSM system .In 1990 , the phase I of the GSM specifications was published but the commercial use of the GSM did not start untill mid 1991 .From the evolution of GSM ,it is clear that the GSM is not anymore only a European standard,GSM networks are operational or planned in over more than 80 countries around the world.