A recent investigation found that cell phones are being smuggled into TN prisons frequently, especially into private facilities run by CCA. As the article properly points out, the COs often bring in the phones because they need extra money and can sell them to prisoners for hundreds of dollars. Why do these guards need more money? Because CCA and other private prison companies don't hire unionized workers, and pay lower-than-market wages to non-unionized, undertrained, often poorly qualified staff. You get what you pay for, Tennessee.
PS - the inmate who shot officer Mark Chestnut, who is now suing CCA for failure to follow even their own policies to keep him incarcerated, was able to escape via a smuggled-in cellphone.