What's the cell phone jammers?
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.
There are many legal purposes for using them in some peoples everyday lives. Cellular based security systems testing, cell phone testing, wireless product testing, and GPS product testing are areas where technicians use them all the time to verify their equipment is working without actually causing unnecessary calls to 911 centers. Many schools, theatres, movie shops, dorms, auditoriums, restaurants, and so forth can also use them legally.