The quarterback signed a one-year contract with the team Monday. He's expected to back up Chad Henne, who replaced Pennington when he injured his right shoulder during the third game last season.
NFL.com's Steve Wyche reported over the weekend that Pennington will earn $2.5 million as Henne's backup, but he will make $4.2 million if he's traded and $5.75 million if he starts, according to a source familiar with the situation.
Pennington, 33, is recovering from a third operation on his throwing shoulder. Twice, he has returned from injuries to win NFL Comeback Player of the Year honors, most recently in 2008, when he led the Dolphins to their first playoff berth in seven years.
During that first season in Miami, Pennington made an immediate impact by helping lead the team to the biggest single-season improvement in NFL history, 1-15 to 11-5 and the first AFC East championship for the Dolphins since the 2000 season.
Pennington spent the first eight seasons of his NFL career with the New York Jets, who made him a first-round draft pick in 2000 (18th overall).
The Associated Press contributed to this report.