The Stampeders also sent their third-round pick (23rd overall) in the upcoming CFL draft to Ottawa for the Redblacks' third-round pick (19th overall) this year. Calgary also gets Ottawa's third-round selection in 2015.
The six-foot-four 240-pound Phillips, who is from the Ottawa suburb of Stittsville, spent the last seven seasons in Calgary where he registered 78 defensive tackles, 78 special teams tackles and four sacks.
"We tried to get Justin during the expansion draft but things did not work out then, but we're glad to be able to acquire such a quality player now," Redblacks general manager Marcel Desjardins said in a statement. "Justin is an Ottawa guy and we believe he's going to thrive in this environment."
The 28-year-old played his university football at Wilfrid Laurier, where he won the 2005 Vanier Cup.
Phillips was selected fifth overall by Calgary in the 2007 CFL draft and won the Grey Cup the following season with the Stampeders.