In addition, thieves have been stealing other electronic devices.
According to The Chicago Tribune, 581 robberies were reported on CTA property in 2010. That's an average of 48 a month.
There were 294 robberies reported through the first half of this year, an average of 59 a month. That is a 23 percent increase.
Police say phone robbers often pounce on victims when a train stops at a station and the doors open. They urge CTA riders to keep their smart phones out of sight.