In some cases, such as in a movie theater, a mobile cell phone jammer will be called. In some places, it is even forbidden to make phone calls; therefore, cell phone signal jammers can be installed in prisons. They block radio frequencies and prevent residents from using smuggled phones. Such “disasters” are illegal in the hands of individuals, and are costly and inefficient. They can also pose a safety risk if they fall into the wrong hands, because they can hinder emergency calls.
As demonstrated by IT scientists at the Technical University of Berlin, even commercially available mobile phones can be converted into jamming stations by changing the software. By doing so, they drew attention to a widespread security breach. A research team led by Nico Golde of the Institute of Software Technology and Theoretical Computing replaced the software on the mobile phone, which was then used by mobile jammers to exploit vulnerabilities in the GSM radio standard. Computer scientists presented their results at the 22nd Usenix Security Symposium in Washington in mid-August.
The optimized open source software is suitable for modified mobile phones. This is how they deceive the radio mast, rather than just flooding the frequency in a small area with false signals such as cell phone jammers. Blocked phones prevent sending text messages and calls to recipients throughout the area: they pretend to have false identities and answer questions on behalf of others.