As the name suggests, cell phone jammer and jammer cellphone were born to prevent radio signals from reaching certain phone numbers. Due to this feature of cell phone jammers and mobile blockers, the specific phone number will disappear from all available networks. The reason for this is that the gsm function of the mobile phone is damaged or blocked.
The size of the cell phone jammer in the classroom will vary depending on the type of device. If you have a strong jammer, the antenna will be located outside to provide better coverage and coverage. Another advantage of adjustable units is that they can be “tuned down” so they will not block adjacent areas.
It can block all types of cell phone signals, you can make calls, receive and send messages, and you can also go online. This means that you must shield the following frequency bands: CDMA/GSM/DCS/PHS/TD-SCDMA/WCDMA/CDMA2000; the effective protection distance must reach 20 meters; the price is reasonable, and the warranty period is more than three years. The school only uses cell phone jammers during the exam and turns them off when you exit.