No confirmation on this from the Flyers or the Phantoms, but there's no reason not to believe John Buccigross.
McDonald, the captain of the Phantoms, has dealt with injury this season and has only played in a handful of games thus far. His last NHL action came in 2014-15 with the New York Islanders.
McDonald's call up is likely a response to the injury suffered by Sam Gagner in Monday night's OT win over Carolina. Gagner left the game after taking a high hit from Hurricanes' Brad Malone, which you can see below.