Cell phone jammers have been around since 1998. Transmission power controls the jamming of radio signals or modulated radio waves. The signal jammer can work in two ways. Some devices place their signals on the same frequency as the pager and cellular phone, separating the traffic between the cellular phone and the base station. In addition to electronic filters, people also spoof calls into thinking they cannot use a frequency to make or receive calls. Interference affects only specific areas (usually within 10 to 100 feet) and can only affect cellular transmissions. Sounds like the perfect solution for mobile phones.
The state government is keen to install GPS jammers in prisons so inmates have no way of communicating with the outside world, but for that the state government needs approval from the Cabinet's Central Security Department - the agency that sets the specifications and frequency of cell phones. These devices. “Recently we got approval from the central government and they commissioned Bharat Electric and Indian Electronics Corporation to do this work. We need offers from these two organizations,” said Foreign Minister Haider Ali Safi.
Kolkata: The state government has decided to install technologically-enhanced WiFi jammers that can restrict voice even when using 4G-connected mobile phones. It will initially be installed in three correctional facilities namely Aliopore Central, Dum Dum Central and Presidential Prison, the first correctional facility in the country to benefit from the advanced technology of this jammer.
“More importantly, as all operators roll out their 4G services, devices currently setting frequencies for 2G and 3G services cannot block voice coverage from 4G-enabled phones. So we ask them to update their devices.”
“We collect 80 to 90 cell phones from prison every month. It is difficult to prevent prisoners from taking them from the outside. With these phones, they can easily control the outside world,” a source inside the prison said.