According to WXYZ.com, McCollum was acquired for a conditional 2018 seventh-round draft pick from the Calgary Flames.
McCollum was drafted by the Wings in 2008 in the first round as the 30th overall pick in the entry-level draft. He went on to spend time in the Ontario Hockey League for a season before playing for the Grand Rapids Griffins in the 2009-10 season.
UPDATE: The Detroit #RedWings acquired G Tom McCollum from Calgary for a conditional 7th round pick in 2018. pic.twitter.com/0ZVyHU7DQd
— Detroit Red Wings (@DetroitRedWings) July 1, 2017
The 27-year-old was signed by the Flames out of free agency last season.