Science Projects And Inventions

Digital Cell Phone

"... only thirty years ago [its functions] would have filled the entire floor of an office building."
Marshall Brain, How Stuff Works
By the early 1980s analog cellular telephone systems were attracting ever more customers. Each country, however, was developing its own standard, which was often incompatible with others.
Standardization seemed essential, and so, in 1982, the Groupe Special Mobile (GSM) was established by a consortium of thirteen telecommunications interests to develop a common cell phone system throughout Europe. (Appropriately, 'the" "acronym was later changed to represent the ''words" Global System for Mobile Communications.") The first GSM phone call was made on the Finnish Radiolinja network in 1991, and by 1997 100 countries had implemented a GSM capable network.
GSM strove to produce a standard for all the elements of a cellular mobile phone call, including the particular frequencies to be used for receiving and transmitting calls. Since the signaling and speech channels of the GSM network are digital, the network is considered a second generation (2G) phone system. Voices are digitized, compressed, and then sent through the GSM network—a far more efficient use of network resources than afforded by its analog predecessor. Also, data could be sent to and from the digital phone at speeds of up to 9,600 bps (bits per second) and, with the appropriate hardware adaptor, documents could be faxed, too. Other GSM services incorporated include call forwarding, call barring, caller identification, and call waiting. Most remarkable and influential of all, GSM introduced the Short Message System (SMS) for text messaging.
The GSM Association, the trade association of GSM, estimates that the standard is used by 82 percent of the world's cell phone users, across more than 210 different countries and territories. 


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