Fantasy Interactive Scenarios by Telephone

Fantasy Interactive Scenarios by Telephone (F.I.S.T.) were a series of single-player telephone-based roleplaying games launched by UK games designer Steve Jackson in 1988 through the company Computerdial, who until then had used their service to provide astrology services. The product was a radio drama version of Jackson's popular Fighting Fantasy novels, and the outcome of the story could be affected by choices the user made, using a touch-tone telephone.

Source: Wikipedia — Fantasy Interactive Scenarios by Telephone (CC BY-SA 4.0)