I like the One Missed Call movie, and all the people at imdb are like it stinks, and it's horrible because they didn't get the movie. Sure, the movie takes some thinking involved into figuring out why things happened. To not give anything away above (the line), I will just say that it's about people being called, and after they are being called, they die.

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SPOILER Alert:

Some of these are my opinions as to what really went on, so take them as you will, and I achieve these opinions because there are clues in the movie.

First off, why did the "evil" sister try to kill her other sister? I believe it's because of jealously. Look in the sisters room, and you see a mother with a kid in a wheelchair. So, where's the evil girl? This is like a statue / doll thing.

What's the point of the school burning? I think the mother was a nurse at the school considering she was dressed in white, and her daughter was also at the school, but she got out alive. Or, it could be something as simple as parent-teacher conference, and they were both at the school. The evil girl is mad at the mother for shutting the door, and not helping her (and her dying), so that's why she attacked the mother at the school. I wouldn't even be surprised if the mother rigged the inhaler so it wouldn't even work.

How does the phone thing work in relation to how are the people picked? First, the evil girl called her mother because she was killed. Than, the mother died in the school. You see her with the phone in her hand. Than, I think the black girl who died in the pond was probably a babysitter called by the mother, and than the babysitter called her friend, and so on and so forth.

As someone has said on imdb: The person that ... "died called the person who mattered the most in their life"

Why was the phone ringing at the end? Did you notice there was no voice mail unlike all the other times. I think the point of that was that the evil girl is gone for good.

I thought this was a great movie. Maybe, sure it needed a little bit more explanation, but I just see it all there in the movie. You just have to look for it.