Usually, when people make phone calls with their mobile phones, they convert all the operations on the phone into data, and then transmit the data through electromagnetic waves. Electromagnetic waves associate mobile phones with signal base stations within a certain frequency range, and then complete data conversion and transmission through specific baud rates and modulation methods. The networking between signal base stations is achieved through optical fibers or microwave circuits. The coverage range of signal base stations is limited, and if you happen to be at the edge of the coverage range, there may be signal attenuation.

Frequency jammers usually intercept electromagnetic waves emitted by mobile phones and connect them to signal base stations. Interrupted communication between the mobile phone and the signal base station. The frequency jammer will emit random static electricity or noise over a wide frequency range, making it impossible for devices close to the jammer to connect to the signal base station, such as a sports car engine starting and you making a phone call nearby. The local noise is strong enough to prevent the device from connecting properly, effectively blocking the normal operation of the phone signal.
The frequency jammer also emits electromagnetic interference signals, which have the same carrier frequency as the base station signal. Therefore, it interferes before the mobile phone receives the communication signal, making it unable to receive the signal emitted by the base station, thus successfully interfering with the use of the mobile phone.