GLOBAL SYSTEM FOR MOBILE COMMUNICATION
GSM is a second generation of cellular telephone system system developed to solve fragmentation problems. It is the first digital cellular telephone system to use services of wide range of network services.

GSM PARAMETERS
200 KHZ TRAFFIC CHANNELS, 992 FULL DUPLEX CHANNEL, FDMA/TDMA ACCESS, 890MHZ to 915 MHZ mobile transmit band (reverse channel), 935MHZ to 960 MHZ base station transmit band (forward channel), GSM uses two 25 MHZ frequency for system use in all member companies.

Additional Services
SMS, Cell broadcasts, Voice mail, Call Baring, Call forwarding, Call hold, Call waiting, Caller identification.

GSM Security Features
The previous analog based systems were very insecure as data sent was not encrypted and any one can break in the conversation. He just needs a receiver to tune in that frequency. But the digital communication system uses encryption techniques to secure its data sent from eavesdroppers.