The Phone (2015)
Since his wife has been murdered, Dong-ho has lost the light in his life. The successful businessman is broken and falls into depression, though he tries to continue with his life. But as long the killer is still out there, Dong-ho can't come clean with his loss. Then one day he gets a call and can't believe his eyes: he is talking to his dead wife! First he believes this must be a bad joke, but the woman knows things only his wife can know. Dong-ho can't believe his luck, because now he has the chance to safe her life, but he has to be as quick as possible. He thinks a magnetic field anomaly allows him to talk to his wife. Which means that he has to identify the killer and warn his wife before the anomaly disappears again.