Cellular (2004)

About Cellular

A woman is kidnapped out of her house and brought somewhere and locked in a room. Now there's a phone in the room but before she could use it, her captor smashes it. She then tinkers with it and manages to get a dial tone but is unable to dial. She then crosses wires and contacts a young surfer. When she tells him that she has been kidnapped; he doesn't believe her and/or care but he goes to the police to report the crime. When he gets to the station he gets the run around. While waiting he hears the woman's conversation with her captor and learns that her family's in danger so he tries to help them but in the process of doing that he commits some acts that make the police think he's a criminal or crazy; like stealing a car and brandishing a gun in public.

Source: http://www.imdb.com/title/tt0337921/plotsummary