A cell phone jammer is a device that blocks cellular phone signals within a certain radius, preventing a person from making or receiving calls. It can also divert incoming calls to voice mail. It jams the downlink frequencies in cell phone systems using advanced electronics and radio frequencies.
A cell phone jammer is commonly used in places where cell phones should be turned off for ethical reasons such as theaters, schools, restaurants, libraries, churches, concert halls, and hospitals. The downside of using one is that it also blocks important telecommunications such as emergency radios and other types of wireless communication. In the US, using a cell phone jammer is illegal. Anyone caught using one can be fined with $11,000 or jailed for a year. Ironically, the US is one of the largest markets for cell phone jammers.
