Smooth Operator (1986)

We never get to see the Smooth Operator because he's only a voice on the phone. He knows just which girls to call to get the most exciting obscene responses to his midnight messages. He calls a gorgeous, long-haired brunette and she tells him her fantasy of meeting him in a deserted warehouse and taking him on a work table. Then an exotic blonde relays her story about watching her girlfriend make it with three studs at once. Naturally, we get to see her fantasy, too.