Signal jammer can block the cell phone signal as soon as your turn it on. Apart from the cell phone signal, it can also block the Wifi signal which is widely adapted by the smart phones today. And it can block the GPS signal when you drive the car.
https://www.dojammer.com/

According to the Wuhan City Licensing Office, after completing the English listening test, the cell phone jammer can be turned on and work normally; After the test, the cell phone jammer may only be turned off after all candidates in the exam room have left the exam room. Cell phone jammer It can block signal reception for a period of time, giving us more time to rest.

https://www.dojammer.com/wirel....ess-wifi-blockers.ht

Is it as safe to use a GPS jammer as it is to use a mobile phone while charging? | #gps

Is it as safe to use a GPS jammer as it is to use a mobile phone while charging?

The device will act like an amplifier that produces a lot of noise in all directions, which would interfere with your cell phone’s network connection or even prevent it from working altogether.

LIFEALERT® is a medical device that monitors the heart rate and transmits the data to a central server. If you are using a signal jammer, he will not be able to detect his heartbeat, so he may think he is dead. This could lead to serious harm or even death!
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Control the time when children play games: Use the full-band cell phone signal jammer device to reasonably control the WIFI network signal of mobile phones, so that students' mobile phones cannot play games online within a specific time. Reduce the conflict in the communication process between children and parents.
https://www.dojammer.com/cell-phone-jammers.html