How to identify whether someone has installed a signal jammer?

First of all, cell phone jammer need to be plugged in, so you can observe whether there is such a device near the power socket;
In addition, the appearance of the mobile phone signal jammer is also quite special. When you see a metal device with 6-10 antennas as long as chopsticks, it also shows that this is a mobile phone signal jammer; some mobile phone signal jammers do not The antenna is a large box with a plastic shell, or it may be a shield.
Finally, observe the signal strength of the mobile phone. If the mobile phone has no signal or no service, and cannot make calls and surf the Internet, it means that a mobile phone signal jammer is installed.