Birmingham City have confirmed that they have released four players following the conclusion of the Championship season.
Caldwell has immediately gone on loan to MLS side Toronto until his contract at St Andrew's expires on June 30.
The club posted on their official Twitter account: "[Birmingham City football club] can today confirm that Paul Robinson, Jonathan Spector, Wade Elliott, Colin Doyle and Akwasi Asante have all been offered new deals.
"Meanwhile the quartet of Steven Caldwell, Keith Fahey, Morgaro Gomis and Pablo Ibanez have all been released. Steven Caldwell will now spend the remainder of his current contract (due to expire on June 30) on loan at MLS side Toronto.
"We'd like to thank Steven, Keith, Morgaro and Pablo for their service to the club and wish them well for the next chapter of their careers."
Caldwell, Gomis and Ibanez all spent two years at Birmingham, while Fahey made over 100 appearances for the Blues since he joined the club in 2009.