How to block cell phone signal in college classroom?

Nobody’s arguing that mobile phones aren’t extremely useful and even necessary in the modern world. Most people have at least one. Perhaps you’re reading this article on an iPhone or Android tablet yourself! It is hard to think of a single area of our life not being affected by the use of mobile devices of some sort. There is no denying that students do have a great deal of harm in using mobile phones in school: In this case, you only need to open a GSM jammer during class time and exam time. Typically, students use a WIFI signal or a 4G signal. If you're not sure what kind of signals your students are using, you can choose devices that can interfere with both signals at the same time.