Dead Line (2006)

Alone and desolate, Martin Sanders is a recluse whose only form of entertainment comes from eavesdropping on the conversations of strangers. Slowly it becomes clear that he is not simply overhearing the passions of innocents... but the trappings of a serial killer... one that lives in his building and knows Martin has been listening. Now Martin has to find the identity of the killer before he finds his next victim. It is a vicious game of cat and mouse... where no one is above suspicion, there is no one that can be trusted... and the man he is chasing just might be chasing him.