Jason Garrett came to Dallas as offensive coordinator in 2007 and held on to that position after he became head coach midway through the 2010 season. There was no indication of how Callahan having that title would change, if any, Garrett calling plays or other coordinator duties.
Dallas also hired Jerome Henderson as its new secondary coach.
Callahan replaces retiring offensive line coach Hudson Houck, who spent 13 of his 29 NFL seasons with Dallas. Secondary coach Dave Campo spent 18 seasons with the Cowboys, three as head coach. The contracts of both coaches expired at the end of the season.
Campo was part of Jimmy Johnson's original staff in Dallas, where he was first an assistant from 1989-99 before going 15-33 as head coach from 2000-02. He then was an assistant in Cleveland (2003-04) and Jacksonville (2005-07).
In 2002, in his first season as a head coach at any level, Callahan led the Raiders to an 11-5 regular-season record that included the AFC West title and a berth in the Super Bowl. He was fired after the Raiders slipped to 4-12 the following season. He had been offensive coordinator from 1998-2001 before getting promoted.
Henderson is reunited with defensive coordinator Rob Ryan, his boss in Cleveland in 2009-10. Henderson was defensive backs coach for the Browns for the past five seasons.