Facsimile
The successor in “almost-immediately obsolete contraptions” to the telex machine, nowadays the facsimile machine is mostly useful for affording bragging rights, both for those[1] who can remember having to use them and what they were for, and those who can’t[2].
A fax that ran out of paper was an important McGuffin in the denouement of John Grisham's espievie thriller, The Firm. Not to be out-done, Hunter Barkley’s forthcoming novel is going to involve a malfunctioning telex.