Data Source: Federal Communications Commission, Statistics of Common Communications Carriers, 1994. (Graph: Peter Wagner, 2014)

This graph originally appeared in Today the FCC dragged the prison telephone industry kicking and screaming into the 21st century.

Rates are based on per minute cost, in 2013 dollars, of a 10 minute call from New York City to Philadelphia at the night/weekend rate, 1950-1944.