The former University of Florida star is said to prefer returning to the Titans, who released him because of their salary-cap problems.
In addition, the Dolphins also have had visits from cornerback Mario Edwards, defensive end Tony Bryant and safety Travares Tillman, and are expected to meet next week with safety Kenoy Kennedy and quarterbacks Gus Frerotte and Brad Johnson.
Of those, Carter and Kennedy would be two nice additions to the defense, while either Frerotte or Johnson could compete with A.J. Feeley for the starting quarterback job.
On the flip side, the Dolphins lost linebacker Morlon Greenwood to the Houston Texans, who gave him a whopping four-year deal worth $22.5 million and including a $7 million signing bonus -- a hefty payday for a player who in 53 career starts ad zero interceptions, zero fumble recoveries and zero forced fumbles.
Along with Ed Perry, who was re-signed on Wednesday, Greenwood probably was the only free agent the Dolphins would have wanted back, but certainly not at the salary he got in Houston.