Cell phone jammers
Pictured left are two versions of the same handheld cell phone jammer - one with external antennas and one with internal antennas, fit into a pack of cigarettes.
Cell phone jamming devices were originally developed for law enforcement to interrupt and control communications by criminals - in a hostage situation, for instance. But who wouldn’t want their own pocket phone jammer to shut up the person sitting near them in a restaurant who just won’t quit yapping on and on?
How do they work? Jammers block cell phone calls by sending out radio
waves along the same frequencies that cellular phones use. This causes
enough interference between the phone and the towers to render the
phones useless. On most retail phones, the network would simply appear
out of range. Newer models such as the double and triple band jammers
can block all widely used systems and are even very effective against
newer phones which hop to different frequencies and systems when