To make room for Franks on the 53-man roster Thursday, the Falcons waived-injured receiver Tim Toone.
Franks was a fifth-round pick by the Falcons in 2010 and started four games last season. He was beaten out during the preseason by Christopher Owens and Robert McClain for backup roles behind Brent Grimes, Dunta Robinson and Asante Samuel. But the Falcons decided to beef up their secondary depth heading into Sunday's opener at Kansas City.
Toone was a seventh-round pick by Detroit in 2010. He spent time on the practice squad with the Lions and two other teams before joining the Falcons this year.