SPS using ‘stingrays’ to monitor and block prisoners’ calls

The Scottish Prison Service (SPS) has been using IMSI-catchers, devices which mimic mobile phone masts, to monitor and block prionsers’ calls, according to information released under the Freedom of Information Act. It is the first officially acknowledged use of the technology in the UK.

So-called ‘stingrays’, widely used by US police and intelligence services, trick mobile phones in the area into transmitting their locations and identifying information. When used to track a suspect’s phone, they also gather information about the phones of countless bystanders who happen to be nearby.

A heavily redacted report by the SPS, obtained by the investigative site The Ferret, revealed that a trial in two Scottish prisons involving IMSI-catchers was beset with problems. Despite spending more than £1.2m on the equipment, the report cites “resilience issues,” during the pilot and a “lack of intelligence provided by the system.”

The project did not lead to a reduction in the numbers of mobile phones being used in the pilot prisons because prisoners developed what officials described as “innovative countermeasures” to circumvent the phone block. Details of how they outwitted the high-tech system have been redacted from the report released to The Ferret.