Based on the info they got from the wire their mole wore, the group employed lookouts positioned in every stairwell that can notify them when a housing unit's corrections officer leaves. Since it's a low-security prison, they didn't have to worry about more than one guard, but they still hid their phones carefully in light fixtures, closets, under their lockers and in jacket linings.

Feds named Anthony Craig Jeffries, who's serving 14 years for distributing child porn, as the group's ringleader. He reportedly purchased a phone for around $900 to $1,000 and then rented it out to inmates for anywhere between $4 to $10 an hour. Jeffries and the other three were officially charged after the mole got them talking about the videos and images they were downloading from the dark web.

This is far from the first time inmates were able to hide machines from guards and use them for nefarious purposes while behind bars. Back in 2015, two inmates in an Ohio prison fixed decommissioned computers and hid them in the ceiling. They used the computers to take out credit cards under other prisoners' names, create access cards for restricted areas and to download porn.