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Press Release

Prison Test Shows Micro-Jamming May Counter Criminal Threat of Contraband Cell Phones

For Immediate Release
Office of Public Affairs

The National Telecommunications and Information Administration (NTIA) has posted a report detailing its findings from the Jan. 17, 2018 test of micro-jamming technology conducted at the Federal Correctional Institution at Cumberland, Maryland. 

Data from the test show that the micro-jammer’s signal disrupted commercial wireless signals inside the prison cell, which meant that if cellphones were operating inside the cell, they would have been rendered inoperable.  At 20 ft. and 100 ft. outside the cell, however, the micro-jammer signals did not disrupt the commercial wireless signals. 

Department officials present during the January 17, 2018, test reported that while their cellphone signals were blocked inside the cell, their cellphones were operable when standing several feet from the cell’s window.

“These promising test results mark a step forward countering the security threat posed by contraband cellphones,” said Assistant Attorney General Beth Williams of the Justice Department’s Office of Legal Policy.  “The results indicate the potential for localized impact of this micro-jamming technology.  That is an encouraging sign that brings us closer to a solution that will make our communities safer and help prevent the continuation of criminal activity from inside prison walls.”

The data in the report will be used by BOP and the Department to understand the efficacy of micro-jamming, conduct further evaluation of jamming technology, and develop recommendations for strategic planning.   

Contraband cellphones have been an ongoing correctional security and public safety concern for the BOP as well as for state and local correctional institutions.  Across the country, contraband cellphones have been used by inmates to direct gang activity, run criminal enterprises, distribute child pornography, intimidate witnesses, and facilitate the commission of violent crimes.  “This test is just one part of our ongoing efforts to disrupt and disable dangerous contraband cellphones in federal and state prisons,” said Assistant Attorney General Williams.

The BOP will continue to evaluate cellphone detection and interdiction technologies and work with its federal partners and Congress to achieve cost-effective options to combat this threat to corrections and public safety.  The agency does not endorse any specific vendor or product.

NTIA’s full report is available at:

Updated June 20, 2018

Press Release Number: 18-794