As you first knew, cellular signal jammers, gps inhibitors, and any other type of signal interception device are made by the Army. They play an important role in terms of safety, as many modern explosives can be activated by a simple phone call and because no signal is received, no explosion will occur. A few years later, some of the most important manufacturers realized that they could use this technology to make a bigger profit and decided to start making this device for society.
One thing you should know about blocking devices is that they are only useful and dangerous because they are considered blocking devices. As you know, the use of other jammers is prohibited in many countries. Remember, you should know if blocking equipment is prohibited in your country because it is important to know that owning such equipment can be dangerous. If authorities catch him, he will face serious problems and will have to pay fines.
Regardless, once you power on the device, you will see that it will start transmitting white noise at the same frequency, so you can block signals from surrounding phones. Some GPS signal jammer will only block one of these two frequencies, but the good news is that this can still accomplish the task. The phone will assume that it is not receiving the signal and you will not be able to speak. Signal jammers can transmit many different frequencies, and if you are willing to spend more money on this device, you should know that you will definitely get something really good. Also, these devices are very effective for TDMA, GSM, AMPS, CDMA and other mobile standards, so if you also need to block some of them, it will be good to keep this in mind.