GSM jammer To interfere with the mobile phone, you need to broadcast at the correct frequency
GSM is used for digital cellular and PCS based systems. It operates in the 900 MHz and 1800 MHz frequency bands in Europe, Asia and Africa, and in the 1900 MHz (sometimes called 1.9 GHz) frequency band in the United States. Although different cellular systems process signals differently, all cellular telephone networks use radio signals that can be interrupted.
The actual range of gsm jammer depends on their power and local environment, which may include hills or walls of buildings blocking interfering signals. The jammer can broadcast on any frequency and is effective for AMPS, CDMA, TDMA, GSM, PCS, DCS, iDEN and Nextel systems.
The low-power jammer can block calls within about 30 feet (9 m). The unit with higher power can create a cell-free area of a football field (about 120mx90m). The unit used by the law enforcement department can shut down the service up to 1 mile (1.6 km) away from the jamming equipment.