The US government and the municipalities can continue to argue over the legality of the use of the cell phone jammers but the matter of the fact is that some people really find them indispensable. Initially brought into fray for specific military purpose, these devices have now reached a level where companies have started rolling them out as hand-held portable devices. The one we talk about here is good enough to block calls within a radius of 8 to 10 metres meaning that it is the one that blocks signals from the tower to the phone. Capable of blocking eight types of commonly used frequencies including GSM and CDMA, this handheld device would cost the buyer USD 246. Ask me about the pricing and I would call it unjust for a similar price would fetch you a Jammer capable of blocking calls within 30 metres but then the privilege of being handheld is a royalty of course.