phone detector device suppresses signal
Speaking of exams, I believe this is something that everyone is particularly familiar with. In my student days, I actually experienced various exams, both large and small. There are monthly exams arranged by the school itself, and there are also more important ones such as the high school entrance examination. In fact, for the fairness and impartiality of exams, many schools install mobile phone detector device, just to prevent everyone from using mobile phones to deliver answers. I believe that more than one editor has experienced such things, that is, when a mobile cell phone jammer is installed. Still holding a fluke, I took out my phone and tried it, but there was no signal.
Some students pretended to be working around the school and called 10086, saying that the mobile phone detector device had affected their work. How could they let their mobile phones have signals? The answer of the customer service is to wait until others turn off the instrument, or to transfer one's own location, if there is no signal within its coverage area, there is no other way.