Read manga: Kimi Ni Shika Kikoenai

manga
Summary:

A timid schoolgirl who is isolated by everyone, doesn't own a cellphone because no one would call her anyway. So she imagines owning a cellphone in her head, but one day, there is a connection -- the phone rings, and someone is on the line! Note: Tsuzuki Setsuri also did a manga based on the same story. Note2: A movie for this manga was released in 2007, directed by Tatsuya Hagishima.