Since 2018, the Ministry of Justice has spent at least 125 million euros hunting down cell phones in prison. His weapon: the cell phone jammer.

In 2018, Nicole Belloubet, Minister of Justice, announced: “we do not allow mobile phones in detention; this is why we have taken a contract to jam mobile phones, which will be extremely effective”.


To find out, the Eye of 20h took the example of the Health prison in Paris.

Since the renovation of the building in 2019, the hunt for illegal cell phones has promised to be draconian. Five hundred signal jammers have been installed.

But a few hours spent on social networks are enough to realize that communications are not all cut off in 2021 at the prison of Health. Inmates film themselves and post videos from their cell phones brought in from outside. Despite the jammers, residents note that there is still as much traffic of telephones at the gates of the prison.

“We think many cell phones are entering the prison.”

A neighbourhood resident, whose windows of her apartment look directly onto the prison, says: “Do you see that little corner there? We see a lot of mobile phone exchanges. We think there are a lot of mobile phones in jail”.

At the entrance of the neighbouring building, on CCTV images that we have obtained, we see individuals discreetly preparing packages. Food, drugs but also telephones. They then throw their packages over the wall. The prisoners only have to pick them up from the walkways and use a well-honed technique: they fish the packages from their cells with pieces of sheets. And sometimes even exchange them between prisoners.

So why would the signal jammers be ineffective at the Health prison despite a budget, according to the unions, of 7 million euros per year? We were able to enter the prison with the environmentalist senator from Paris, Esther Benbassa, during an impromptu visit.

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

“There are no technologies that work perfectly.”

If on the ground floor, communications seem well cut, on the upper floors, on the other hand, and in particular in the district of the defendants, the telephones work. Bruno Clément-Petermann, director of the establishment, admits the random effectiveness of the device: “the jammers still work in certain parts of the establishment. Afterwards, it’s true that it’s easier when you’re on the upper floors. It poses problems, yes, but we have never had an escape here; there are no technologies that work perfectly”.

Technology, precisely. Simply put, the cell phone jammers provided by a provider company neutralize the 2 and 3G networks. They would only partially jam 4G. And today, the more powerful 5G makes jammers obsolete, and the Ministry of Justice recognizes this.

“Cell phones are a scourge in detention.”

For Erwan Saoudi, regional delegate of the prison union FO Justice, it is urgent to act. And the prison of Health would be far from being an isolated case in France: “mobile phones are a scourge in detention. This allows people still inside to continue their traffic outside and some detainees to continue to harass their victims. This is something that poses a problem for security inside but also outside”.

Contacted, the service provider company that installed the jammers said it was subject to a duty of confidentiality. At Health, 1,200 mobile phones were seized this year. More than one device on average per inmate.

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