Sorry, Wrong Number

Sorry, Wrong Number is a 1948 American thriller film noir. It was directed by Anatole Litvak. Barbara Stanwyck and Burt Lancaster are in the main roles in this movie.
Plot.
The movie is about a woman, Mrs. Stevenson, who is wealthy but mentally ill. She tries to dial her husband's number but she overhears a conversation instead. She figures out that there is going to be a murder at 11:15 and is even more disturbed. She keeps trying to get the operators to trace the call, and when they can't, she dials the police, Sgt. Duffy, but he doesn't help either. Her phone keeps ringing and she gets more worried until 11:15, when the murder happens. Someone is in the house and she doesn't know how to react. She gets her final call from her husband and he tells her to go to the window and scream as loud as she can. However, she doesn't make it in time. We learn that Mr. Stevenson, her husband, was a part of the murder and he killed his wife only for the money, which he regrets.