in public places is illegal. However, if there are government documents permitting you can use.
In the prison cell phone signal jammer
can be used to effectively control the offender contact with outsiders, so in these places use the phone jammers are legal.
Unlike cell phone jammer
signal transmitter, which is a waveform interference, wave superposition. In the design and use very professional.
cell phone blocker
can be controlled with a switch, you can use the time to adjust the demand signal shielding range based on.
In South America, we always use Signal Jammers
as our tools necessary.