The problem is that prisons and jails give companies like the industry leader, Global Tel Link, monopoly contracts in exchange for a share of the proceeds. The companies tack on additional fees to accept, hold and even refund a customer’s money. Global Tel Link, for example, charges $9.50 to make a $50 deposit, and $5 to issue a refund when someone is released from prison or jail. It’s hard to understand why Global Tel Link’s fees are so high, given that the company has 57 percent of the state prison market and its smaller competitors charge far lower fees.

http://www.nytimes.com/2014/02/02/your-money/phoning-from-prison-at-prices-through-the-roof.html?_r=1