Before there was a movie, this story was an urban legend. I'm still kind of scared of it today.
One night a girl was babysitting 3 kids. The night went on normally until the phone wrang. "hello? Is anyone there?" she asked. No, no one awnsered. She hung up the phone and sat back down. Ring! Ring! The phone rang again. She picked it up, a little angry. "Hello?" she said. A raspy voice awnsered on the other line. "one hour from now." "who are you?" the girl said, but then the person hung up. "who was that?" one of the kids asked. "oh just some crazy person" she awnsered. 30 minutes later the phone rang again. "hello?" the girl said. The raspy voice awnsered again "30 minutes from now" and then he hung up. "ok, what is going on!" She thought to herself. 15 minutes later the phone rang... "hello?!!" she said. "15 minutes from now" the raspy voice awnsered yet again then hung up. "that's it!!!" the girl said, "I have to call the police!". The girl dialed 911. "hello? 911 what's your emergency?" the person on the other end said. The girl told them everything that happened. "ok if he calls back, call us and well be over there." then he hung up. A couple of minutes later, the phone rang again "hello?" the girl asked. It was the raspy voice again, "very soon now". The girl quickly dialed 911, and started telling them what was happening, when someone was on the other line. She told the police to hurry, then awnsered it. "NOW" the raspy voice said, almost laughing. Just then the girl heard footsteps in the attic, she ran and grabed the kids. She looked behind her and a man, carrying a knife was chasing her. She ran as quickly as she could out of the house when the police arrived. They arrested the man. He called the girl with a phone in the attic with the wiring set up so he could call her downstairs. No one knows why, but he was smiling on the way to prison.
That last part is extra creepy, it just sends a chill down my spine for some reason.