A person with knowledge of the deal says the Indiana Pacers traded longtime forward Danny Granger and a second-round draft pick to Philadelphia in exchange for Evan Turner and Allen. The person confirmed the deal, first reported by Yahoo Sports, to The Associated Press on condition of anonymity because it was still pending league approval.
Allen was averaging 5.2 points per game for Philadelphia.
After missing one game, Allen made his debut for Indiana in a 118-98 rout of the Los Angeles Lakers on Tuesday.
The center, acquired in a three-player deal with Philadelphia on Thursday, had zero points, three rebounds and one assist in 4 1/2 minutes.
Allen is questionable to play Friday with what coach Brett Brown said is "in regards to his fitness."
Allen has played in all 35 games, but he's seemed bothered by a sore right calf lately.