Dont' quote me on this one, I might be confusing this scene with another movie. I remember a second scene in which this boy (I think) makes threatening calls to an older female. The boy coerces the lady into undressing in front of a window, and on the phone the lady says "Is this what you want to see!" then the lady's daughter walks in and says "Mom!". At the end of the movie the boy is shown walking alone down a deserted road.
This perfectly matches a scene in "The Pit." However, the first paragraph does not.
Click here for a review of "The Pit."
The second movie is a about a female who lost her dad & she misses him so much that she thinks every man that she meets is her dad. The female is in her late teens/20's. She ends up terrorizing all of these unsuspecting men that she meets. I remember a scene in which she is listening to a recorded male voice on an answering machine, and as it plays over and over again she says "I miss you daddy" over and over again while crying. At the end of the movie she meets another guy, has a polite conversation with him and says "You look just like my daddy" (paraphrasing) or something like that.
This matches "Toys Are Not for Children" (1972) in some ways, but I do not believe it is your film. However, the movie you describe could be a re-working of that film.
Click here for the IMDb page for "Toys Are Not for Children."