Cause toujours... tu m'intéresses(1979)

Overview:

François Perrin is a journalist who reads the news on RTL radio. Alone in life, his only "amusement" is his neighbor from Africa, who makes mildly fun of him from time to time. One evening, François is bored, and decides to call a random telephone number. He gets Christine on the line, a bit of an old school pharmacist, who hesitates to put down the phone, and plays the game of seduction with the charming "Mr X"...