A flip-phone-like communicator appears in chapter 3 of "Armageddon 2419 A.D." a science fiction novella by Philip Francis Nowlan, which first appeared in the August 1928 issue of the pulp magazine Amazing Stories. "Alan took a compact packet about six inches square from a holster attached to her belt and handed it to Wilma. So far as I could see, it had no special receiver for the ear. Wilma merely threw back a lid, as though she was opening a book, and began to talk. The voice that came back from the machine was as audible as her own."