Mobile phone signal jammer with complete spectrum interference and long jamming range of up to 8 meters. If you are sick of all those phones going off, then this is the anti-spy gadget you have been looking for. This jammer system comes high power of signal jamming, incredibly easy to operate, just switch it on and it will immediately start blocking CDMA, GSM, DCS and 3G to keep your immediate surrounds annoyance free. The device can be used in museums, meeting halls, exam centers, colleges, concert hall, banks, etc. These Jammers are used to block all cell networks up to 40 meters range. To get maximum efficiency of this genre please dont take off antenna while the machine is working and make sure the all antennas are vertical to the ground (depends on the signal strength in the given area).