Jean Cocteau (1889-1963), also a successful dramatist, wrote La voix humaine in 1928; the first performance took place two years later at the Comédie-Française in Paris. Francis Poulenc, who knew Cocteau for most of his adult life, wrote an opera for soprano and orchestra in 1958 based on Cocteau's play. Gian Carlo Menotti also wrote an opera based on La voix humaine, and Roberto Rosselini, among others, made film versions of the play. Clearly, it makes an impression.
In La voix humaine Cocteau distills theater into a particularly pure and intense form. It is a monologue, a woman speaking on the phone with her ex-lover (though the old phone system plays an important role(*)), and is a very demanding tour de force for actresses, including Simone Signoret, Ingrid Bergman and Liv Ullmann. Cocteau has the actress play the full register of emotions, and, of course, as a consummate artist, he starts softly, tenderly and through a series of increasing intermediate climaxes and revelations leads the audience to a moving conclusion which I won't spoil.
You can listen to the entire play on YouTube as realized in 1957 by Berthe Bovy, who created the role in 1930:
And you can also listen to the wonderful Ingrid Bergman's performance of an English translation:
(*) I wonder how many people even know what a "party line" was...