Authorities say the man then lunged toward the phone and jumped over the security railing, ultimately landing in the freezing cold river.
The man's two companions quickly jumped in after him, but were unsuccessful in their attempt to save him.
The cellphone owner and another male, 23, were ultimately pulled out of the water by diver rescue teams. The 23-year-old remains hospitalized in stable condition.
A 21-year-old female who jumped in the water remains missing and is presumed dead.
"We continued efforts for over an hour, rotating divers, searched for the final victim, were unsuccessful, and now the scene is turned over to the Chicago police for recovery," Chicago Fire Department rep Linda Parsons told WLS.