INVESTIGATION. The impossible jamming of cell phones in jail

Since the renovation of the building in 2019, the hunt for illegal cell phones has promised to become draconian. 500 wave jammers are installed.

But a few hours spent on social networks is enough to realize that by 2021 in the health prison, communication is not all interrupted. Inmates film themselves and post videos from their cells with phones brought in from outside. Despite the lamentations, local residents note that there is still just as much traffic of phones at the prison gates.

“We think a lot of cell phones are coming into jail”

A resident of the neighborhood

A resident of the neighborhood, whose windows in her apartment face directly onto the jail, says: “can you see the little spot over there? We see many exchanges of laptops. It is believed that there are many mobile phones on the way into the prison”.

At the entrance to the neighboring building, we look at video surveillance images that we have received, people discreetly preparing packages. Food, drugs but also telephones. Then they throw their packages over the wall. The detainees only have to pick them up from the walks and use a polished technique: With pieces of the sheet, they fish the packages from their cells. And sometimes even exchange them between prisoners.

So why should the jammers be ineffective in the health prison despite a budget, according to the unions, of 7 million euros a year. We were able to enter the prison with the ecologist senator from Paris, Esther Benbassa during an impromptu visit.

In the fight against mobile phones, the health prison is another example, the first establishment in France equipped with a system of new generation jammers.

“There are no technologies that work perfectly”

If the communication on the ground floor seems well cut off, on the upper floors on the other hand, and especially in the defendants’ district, the telephones work. Bruno Clément-Petremann, director of the company, admits a random efficiency of the device: “The jams still work in some parts of the company. Afterwards, it is true that when one is upstairs, it is easier. It causes problems, yes, but we have never had an escape here, there are no technologies that work perfectly”.

Technology, exactly. To put it simply, the jammers provided by a provider company neutralize the 2 and 3G networks. They would only partially block 4G. And today, the more powerful 5G is making jammers obsolete, the Justice Department acknowledges.

“Mobile phones are a nuisance in detention”

For Erwan Saoudi, regional delegate from the prison association FO Justice, it is urgent to act. And the health prison would far from be an isolated case in France: “Mobile phones are a nuisance in detention. It is what enables people who are still inside to be able to continue their trade outside, it also gives some detainees the opportunity to continue harassing their victims. This is something that poses a problem for safety inside but also outside.”.

The contact said the service provider company that installed the jammers said it was subject to confidentiality. At Health, 1,200 mobile phones were seized this year. More than one unit on average per inserted.


Finance Act for 2022 / Appendix Prison Administration

Department of Prison Administration / Tender Notice (23/01/2016) / Procurement and maintenance of a solution for the detection and neutralization of illegal communications in prison institutions in the metropolitan area of ​​France and abroad.

Directorate of Correctional Services / Announcement of contract award / “Procurement and maintenance of a solution for the detection and neutralization of illegal communications in prison institutions in the metropolitan area of ​​France and abroad.

Installation of jammers in prison institutions / Written question no. 23227 by Mr. Cédric Perrin (Territoire de Belfort, LR), published in the JO Senate of 10/06/2021.

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