David Murphy will remain at Birmingham for a further two years after an extension clause in his contract was activated.
Caleb Folan has joined Championship promotion chasers Birmingham on a free transfer until the end of the season.
Lincoln defender Cian Hughton has signed a new contract to keep him at Sincil Bank until 2011.
Lincoln are confident Cian Hughton is close to signing a deal to stay at the club until the end of the season.
Cian Hughton hopes to secure his future at Lincoln after opening contract talks with manager Chris Sutton.