"Spectre's Call" is the European subtitle for the game, not necessarily a strict translation of the Japanese.
A call can be an instrument producing the sound of an animal, used to lure that animal (a
duck call for instance). I don't know if that's the meaning of call they were going for in the title, because the titular flute is in fact a flute, but it's used to summon the specter so figuratively it kind of works.