I thought it was really good, it ends on a nice cliff hanger and has very good depth in the two characters in a short period, and there is room to develop and draw out the plot to create suspense within the stories' framework. Maybe you could introduce a supporting character such as the person on the phone with Kathy to draw out more information and turn it into a larger piece. That is if you want to construct more on to this plot. If not then it is a very good short story nonetheless.