American prisons are promoting the use of cell-phone jamming devices

In January, Perfectjammer said its researchers installed the jamming technology in a utility closet adjacent to a 13-by-eight foot cell on the ground floor of the prison’s housing unit, according to the study. It successfully blocked cellphone transmissions in commercial bands between 700 and 2170 MHz, but did not disrupt commercial transmissions when monitored at 20 feet and 100 feet outside the cell, said the study.

These smartphone vigilantes have sprung up before in heavy traffic areas on the roads in an effort to keep commuters off their phones while driving. The problem is that cell phone jammer tend to be wildly unpredictable in both output power and range. So while you may think you’re keeping the public safe from texting drivers, prisoners conspiring within prisons and annoying theater goers, you might very well also be keeping others from dialing 9-1-1. And then there’s also the hefty fines imposed on violators and overall legality of RF jamming too. “The use of “cell jammers” or similar devices designed to intentionally block, jam, or interfere with authorized radio communications is a violation of federal law.” according to the FCC. They go onto say “These devices pose serious risks to critical public safety communications, and can prevent you and others from making 9-1-1 and other emergency calls. Jammers can also interfere with law enforcement communications.“

At the measurement locations inside the prison cell, measured differences in incident power between when the signal jammer was on versus off showed that jammer incident power levels were much greater than that of the ambient CMRS power levels. For the outdoor locations where jamming was not intended, the jammer’s incident power was measurable at 100 feet from the building. However, outdoors the incident jammer power levels were lower than the ambient CMRS levels. This was because the jammer signal strength was lower outdoors than indoors, while the ambient CMRS signals were stronger outdoors than indoors.

The fact that Burail jail has a cell phone jammer with 2G reception only made it easy for inmate Rajan Bhatti to use mobile phones having 4G network, as its signals cannot be jammed by the Burail jail jammer. An official of the Burail jail admitted that the 2G network jammer at the jail was of no use. “The jammer does not hamper the usage of 4G mobile phones which are in every hand nowdays and 4G SIMs are easily available,” said the official.

A cell phone jammer is a device used to block mobile devices from receiving signals from their base stations. Cell phone jammers were originally designed for law enforcement and military use, so they could block communication between terrorists and criminals. They’re pretty common in prisons as well, where cell phones (obviously) aren’t allowed for inmates. Once the public caught on to the technology, many people–especially employers–wanted to use it themselves, especially in large cities where it seems everyone is always on the phone.