True 20 years ago, on 07/01/1991, calls the first history of GSM (Global System for Mobile) is made ??by the prime minister of Finland, Mr. Harri Holkeri to the deputy prime minister based on network of Nokia Siemens phone Nokia 900 Mhz frequency. GSM technology after 20 years of development, to this point has connected more than 1.5 billion people in 200 countries around the world, large and small, accounting for 80% mobile phone market worldwide. GSM digital system is the first mobile to use TDMA (Time division multiple access - technology division multiple access over time) that will help convey more information with better sound, worth a call more reliable and use less energy. Along with the development of GSM, a lot of innovation on mobile was created: SIM (Subscriber Identity Module) - cards are used to identify mobile subscribers, is used in mobile network systems GSM, SMS (Short Message Services) - telecommunications protocol for sending short text messages to and MMS (Multimedia Message Service) messages have the format based on GPRS (General Packet Radio Service) - General Packet Radio Service, assist device to access the network (Internet) at all times.