[Help] Movie of a girl hiding a week every night from a monster

Hello! I’m looking for a movie since years ago and still nothing. It’s about a girl that lives in a big house and her parents are always busy and she wants more of their attention so she decides to look over the net and she finds out about a ritual of some kind of a game that if she complete it something will grant her a wish. The game is about she leaving a cellphone in a room then turn off all the lights and she must call to that cellphone, when doing so a monster answer the phone and a hide and seek-like game start so she must hide from that monster every night for a week or so and every day becomes harder, the monster is some kind of half beast or so I remember not sure… at the end the girl wins the game but she end up in a mental house all grow up telling the story… please help​:pleading_face::pleading_face::pleading_face: