How should we prevent thieves from using mobile phone jammers?

Thieves can obtain illegal cell phone jammers. They vary in size, from small portable devices to large briefcases. They send signals on the GSM frequency. This prevents the GSM tracking device in the vehicle from sending and receiving messages. The signals sent by these illegal devices formed bubbles around the vehicle, very effectively "quietly" tracking the device, and no one knew what was going on. This happened recently in Congress. Large cell phone jammer have been deployed throughout the U.S. Congress, which can effectively block all GSM signals in the House of Representatives.

Tracking equipment has three main requirements to resist interference. First, the device must be able to detect signal interference. Next, he needs to send an urgent message to tell someone "I'm trapped". The third and most important point is that you need to be able to send this emergency message at a frequency different from the blocking frequency. Beware of crooks-if there is no other unobstructed frequency, the solution will fail.