France legalized cell-phone jammers in movie theaters
GSM international roaming refers to the GSM cellular mobile telephone users when they leave their home network, you can still continue to use the GSM mobile phone network to communicate with other countries and in other regions. The GSM Jammer can be very easy to block these signals.
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Knowledge: GPS signal is referred to U.S. commercial GPS. The GPS jammer is such a signal shielding devices, can be used in vehicle tracking and so on.