Global System for Mobile communication (GSM) is the most widely used digital mobile telephony system. GSM technology was first launched in Finland in 1991. It was developed by European Telecommunications Standards Institute (ETSI) to describe the protocols for 2G mobile communications.Presently, GSM comprises of approximately 90% of mobile connections worldwide.
Original 2G standard was a digital, circuit-switched, full duplex network.
GSM is part of the evolution of wireless mobile telecommunications including High-Speed Circuit-Switched Data (HSCSD), General Packet Radio Services (GPRS), Enhanced Data GSM Environment (EDGE), and Universal Mobile Telecommunications Service (UMTS).
GSM operates at either 900 MHz or 1800 MHz frequency bands of the electromagnetic spectrum.It provides improved spectrum efficiency.
It uses a variation of time division multiple access (TDMA) for placing multiple calls simultaneously over the same channel.
It gives support for a number of new services like
Digital technology assures high-quality voice communications and advanced encryption of voice and data signals that prevents eavesdropping.