If a signal jammer is installed in the examination room and the mobile phone can still send messages, the jammer may not have an effective interference signal. Here, it may also be that the accessory communication base station is relatively close, resulting in poor signal interference and indirect interference, or that the Signal Jammer does not update the latest 5g interference frequency band. When purchasing Signal Jammer, the latest 5g version of jammer must be selected. The interference frequency band must include: 2G, 3G, 4G, 5g signal frequency band and WiFi 2.4, WiFi 5.8 signal frequency band, so as to achieve good interference effect. If the environmental communication signal is relatively strong, it is necessary to use higher power interference products to achieve good interference effect. Therefore, when purchasing standardized signal interference products, we must identify good brand manufacturers to ensure better interference effect.