A melodrama tends to put its character into danger in order to draw upon the emotions of the viewer (or reader). This plays depend upon exaggerated characters and events which draw the viewer (reader) in and forces the viewer to possess an emotional attachment to the story, its action, and the characters alike.
Although the action of Lucille Fletcher's play "Sorry, Wrong Number" would tend to be melodramatic, one fact nullifies this identification: Mrs. Stevenson. One could argue that Mrs. Stevenson is bed-ridden nature fails to support the exaggerated events which would define the play as a melodrama. Mrs. Stevenson is, most assuredly, a dramatic and emotional character. Her willfulness and desperation due tend to speak to her being a melodramatic character, yet her bedridden nature diffuses this. Although the action of the play, hearing snippets of crossed conversations about murder, can be defined as dramatic, Mrs. Stevenson's overacting can leave one feeling as though she is simply too bored to think through what she could have heard. While her actions, screaming into the phone, provide a somewhat melodramatic action, nothing takes away the fact that she is an invalid. She cannot do anything but lay in bed and scream at the phone. This, alone, proves the play to not be truly melodramatic.