No electronic equipment in the range of the jammer can be used normally

The prisons are littered with cell phones so that inmates can live freely from locked doors and barbed wire. Why isn’t technology used to stop it?

Thousands of cell phones are seized in British prisons each year and many more – dragged in or thrown over the wall – will go undetected.

They are a valuable illegal resource – they only cost between £ 400 and £ 1,000 to borrow.

In 2013, the National Offender Management Service (NOMS) confiscated 7,451 cell phones and SIM cards in prisons in England and Wales.
They used them to “order murder, plan escape plans, import automatic firearms, and order drug imports,” NOMS said. “The problem is widespread.”
Machine guns were smuggled into Britain by a prisoner who organized the crime by phone from his cell. Judge David Farrell QC called the “totally inadequate” prison security that made the crime a “scandal”.
The inmates organized a cocaine ring, ordered the murder of a youth as part of a feud, and organized the killing of a gang leader – all from their prison cells.

The mother of an inmate at HMP Northumberland claims “the place is full of cell phones”.
“There are people who throw cell phones over the fences, and then there are prisoners who have access to the premises so they can bring them in,” she says. Glyn Travis of the Prison Officers’ Association (POA) says the prison is far from unique.
“Drugs and cell phones are thrown freely into prisons,” with the drones “completely undermining the outside security that protects the public,” he says.
Sodexo, operator of HMP Northumberland, said: “Employees have worked hard to prevent illegal items from being jailed through a number of technical and intelligence measures.”
But the fact that so many phones get into prisons despite security precautions partially explains how difficult it is to find and remove them.
The obvious solution, says the POA, is to make it unusable.
cell phone jammer or grippers that block signals or route them away from their intended destination are readily available.

Four ways to interrupt communication Block / Block: A signal is sent to prevent the handset from receiving the signal from its base station. All phones and SIM cards that are within range of the Jammer are blocked, including those belonging to the prison staff. The method is cheap and mostly effective. Disruptions caused outside the prison can be avoided with caution, but this can increase costs.
Grabbing: Phones are attracted to a fake network. It is selective – residents’ employees or phones can be put on an unaffected “white list”. Success can be quantified – phones and their owners can be identified. Illegal phones can be monitored and not blocked. It is more expensive than ceiling jam.
Business interruption: The 2015 Law on Serious Crimes introduced the power to force cellular operators to disconnect illegal phones. The relevant regulations have not yet been adopted. Separate phones and SIM cards can be replaced and mobile operators may not be willing to work together.
Stop and search: Visitors and employees can be searched for illegal phones. Cells and inmates can be searched to find those who have been overlooked. Sniffer dogs can be trained to find cell phones. Some phones are stripped of detection and new ones can be used to replace the seized

In the above four modes, using a jammer to block the communication signal is the most effective method: it is fast, secure, and saves money.