Kelly was Oregon's offensive coordinator when Dixon was the Ducks' quarterback. He spent last season on the practice squad of the Super Bowl champion Baltimore Ravens.
Dixon, 28, was drafted in the fifth round of the 2008 draft by the Pittsburgh Steelers after throwing for 2,136 yards with 20 touchdowns and four interceptions, completing 67.7 percent of his passes under Kelly at Oregon before tearing his ACL in the 10th game of the 2007 season. He also rushed for 583 yards.
In the NFL, Dixon has appeared in four games, all with the Steelers, completing 59.3 percent of his passes for 402 yards with one touchdown and four interceptions. He also has rushed for 24 yards and a touchdown.
Vick signed a one-year contract this week to return to the team, and Kelly said he would compete with Foles for the starting position.