Mysterious Notebook

One day, I was trying to gather information from the books at home so that I could do the homework given by my teacher. Just as I was picking up a book, a notebook fell on the floor. At first, I was very scared, but then I put the book in my hand on the table, picked up the notebook that had fallen on the floor, and started examining it. At first, everything was normal, but when I came to page 120, I saw a phone number that was written by hand. I didn’t want to get too involved because I thought it was an old trick, but the number looked like it had just been written, as if the ink hadn’t dried yet. I took the notebook and went upstairs to my room and tried to ring the number from the phone, but the number was not in use. I feel like I’m dying of curiosity. Even if I were, there was nothing to do.