The full name of GSM: Global System for Mobile Communic ATI ONS, Chinese as the global mobile communications system, commonly known as "GSM", originated in Europe is a technology standard for mobile communications, is the second-generation mobile communication technology, developed to so common around the world can use a mobile phone network standards, allowing users to use a cell phone can be marketed around the world. China in the 20th century, the early 90s with the introduction of technical standards, had been simulated using cellular mobile technology, the first generation of GSM technology (December 31, 2001 China closed the analog mobile network). Currently, China Mobile, China Unicom GSM each have a network of the world's largest mobile communications network. GSM system, including GSM 900:900 MHz, GSM1800: 1800MHz and GSM-1900: 1900MHz, and several other bands.
GSM system has several important features: copy the best personal security, network capacity, mobile phone number is rich in resources, the call clear, strong stability and less susceptible to interference, the information is sensitive, less dead call, the phone power consumption low.
At present China has two systems for the GSM 900 and GSM GSM1800, the use of different frequency, so for mobile phones are not the same. However, most of the existing dual-band mobile phone is basically, you can freely switch between these two bands. European countries are using GSM900 and GSM1800 systems other than to join the GSM1900, for the tri-band mobile phone. With the mobile phone market in China further development, now also have been a tri-band phone can be in GSM900 \ GSM1800 \ GSM1900 free switching of three band mobile phone, a phone can really swim all over the world.
Early look, GSM900 development in time, the use of more, whereas GSM1800 development time later. Physical properties, the former is lower spectrum, longer wavelength, less penetrating, but the transmission distance, while the mobile transmit power strong, power consumption, so the standby time is shorter; However, the high frequency spectrum , shorter wavelength, good penetration, but the short distance transmission, its low transmission power the phone, long standby time accordingly