The GSM jammer is an electronic device that blocks the transmission of signals between a cell phone and a base station. By using the same frequency as a mobile handset, the mobile phone jammer creates strong interference for the communication between the caller and the receiver. It is effective in blocking the transmission of signals from networks including UMTS, 3G, CDMA, GSM and PHS.
Cell phones operate on different frequency bands in different countries. For Canada, the 1900 MHz band is the primary band, especially for urban areas. 850 MHz is used as a backup in rural areas. The United States uses bands of 850 and 1900 MHz, depending on the region. Europeans tend to use the GSM 900 and 1800 bands as standard. The Middle East, Africa, Asia and Oceania also use these frequency bands. In Russia and some other countries, local operators have licenses for the 450 MHz frequency to provide CDMA coverage.