Leon Kingsley drapes his blanket over his bunk for privacy while he speaks to us. Leon Kingsley

There is a long and sordid tradition of business going on in American prisons.

The isolated consumer base, the high demand for goods, the excruciatingly limited supply — it's a hothouse of entrepreneurial finesse, extreme risk — and obscene returns.

The biggest selling items behind bars have always offered a slice of escape. Not a file, or a schematic of the pipes leading outside the gates, but an instant of abandon allowing an inmate to forget about his life and to live outside the walls, if only in his mind.

Until recently that meant drugs, and the slippery trick of allowing the mind to believe it was someplace else, but that has changed.

There are still drugs in prison, but now there's a better escape that for the enterprising and charming convict may even generate a source of monetary return: smart phones. It's no secret, prison cell phones are in the news and we wanted to see what we could find out.

To learn more about the "hustle," what inmates call any moneymaking scheme in prison, we rented a P.O. Box and sent off letters to a handful of American prisoners. Among others we heard from Leon Kingsley (not his real name) who eventually talked to us on a smart phone away from the prying eyes and ears of penal officers. Kingsley says that a $20 basic phone earns the guards that sell it an easy $400 to $500. Kingsley sent us the pictures here to prove what he says is the truth.

"And the police will do it, too, because they get paid very little," Kingsley, who's serving a 10-year state sentence and 110-month federal sentence, says "But if you use the phone and sell time off of it to the other inmates, you'll make your money back in one month."

"There's a lot of money in here...a lot of money you can make. If you have a good officer, you can make $4,000 or $5,000 a week."

If the phone has wireless capabilities, it can cost the prisoner — or their people on the outside — as much as $1,000. With high-speed internet access, Kingsley says the inmates will make Facebook accounts, "meet girls and get them to send money."

For $50, the inmates can purchase 15 hours of phone time, typically broken up to an hour a day, 30 minutes at a time. Although most inmates use these precious moments to call friends and family, there's also the opportunity for convicts to contact co-defendants and witnesses — such as the alarm caused when authorities found unauthorized cell phones in convicted serial killer Charles Manson's property.

Leon Kingsley's cell Leon Kingsley Through what Kingsley calls "word on the street," prisoners usually know which guards will help them bring in contraband, the same way that civilians who want illegal goods know where to go and who to ask.

"You just try them up, you have to get talking to them," he says.

If the officers agree to deal, the inmates have cash sent in.

Aside from cell phones, anything that you can't buy at the prison store (commissary) has value on the inside.

Kingsley says a can of Bugler tobacco — which goes for around thirty bucks — can be broken down and sold for $1,200. An ounce of pot that costs $100 "on the streets" will go for $600 or $700 behind bars.

"There's the weed man, the meth man, whatever you want. And your friends will tell you these things."

In order to conduct business with one another, the prisoners have credit cards — most of them use Green Dot Reloadable prepaid cards, which their loved ones can purchase at drugstores.

Once the people "on the outside" purchase money packs to put on the prepaid cards, they'll receive a security code, and the people "on the inside" can use these codes to purchase whatever they want. Their sellers will then call a 1800-number, "give them the code" and have the money downloaded onto their own credit cards.

"A lot of stuff in here is run by the gangs...there's the Mexican gangs, the Bloods, the Crips. They all run their own shit. They keep their business pretty good and they don't F*** each other over."

"They always say that they were already in gangs before coming into prison, but a lot of them are weak people forming up with others so no one runs them over."

A bunk in prison Leon Kingsley "I mean, I'm not in a gang and I do fine," he says.

When you're involved with anything illegal — even if you're already in jail — you run the risk of "catching" new charges, but Kingsley says he "hasn't seen it getting done."

When he was caught with a phone, Kingsley tells us he received a written a disciplinary report (DR), which required him to go to the prison court.

With a D.R. citation, Kingsley says the officers might restrict your commissary privileges, deny you from making legitimate phone calls or receiving mail for 90-days, but most likely, the offender won't catch new charges because the officers try to "sweep it under the rug."

"They know the cops are bringing it in, not the prisoners. And they don't want news of that getting out."

Kingsley says the officers will do a "clean up," where they check the cells, twice annually, and confiscate anything unauthorized. This gets expensive for inmates so they hide their contraband, like phones, in food and in "places where [they've] cut into the walls," under boxes and inside furniture if they can manage to take it apart.

"It's a constant racket for officers to make more money really, because they'll take our stuff so we can sneak in more stuff and pay them all over again."

Kinsley shares an open cell with 40 other people. He has about five years left to serve on his sentence.