The story revolves around a humorous incident where the dial-a-joke service features the number 255-6666. Unbeknownst to the users of this service, the number 666 is famously linked to the concept of the "number of the beast" as described in the Book of Revelation. This adds a layer of irony to their choice of phone number for a lighthearted service.
The context comes from Walter Isaacson's biography of Steve Jobs, which details the visionary's life and contributions to technology. The juxtaposition of an innocuous joke service with a number associated with ominous connotations highlights an interesting coincidence in a narrative that explores Jobs' character and influence.