Curtis was recalled from Triple-A Lehigh Valley on Friday.
It's a somewhat surprising call-up, as the Phillies already have a pair of lefties in the bullpen in Adam Morgan and Austin Davis. Morgan hasn't been particularly impressive, though, and Davis has recorded just a single major-league out, so Curtis has a chance to impress and stick around. The 25-year-old has a 4.33 ERA in 27 career big-league innings, with an ugly 21:23 K:BB. Jake Thompson was optioned to Lehigh Valley in a corresponding move.