Curtis was claimed off waivers by the Phillies on Monday.
Curtis will join the Phillies after being designated for assignment by the Mariners last week. The 25-year-old southpaw only appeared in three games for Seattle this season, but he compiled a fine 3.51 ERA and 60 strikeouts in 51.1 innings with Double-A Arkansas. Curtis should offer low-leverage bullpen depth for Philadelphia down the stretch.