Sorgi had been the third quarterback for the past four games after hurting his right throwing shoulder in practice.
Painter, a Purdue alum, was a sixth-round draft pick in April.
The Colts also signed offensive lineman Michael Toudouze, their fifth-round pick in 2006, to fill Sorgi's spot. They waived quarterback Shane Boyd from the practice squad and signed former University of Buffalo quarterback Drew Willy.
Copyright 2009 by The Associated Press