Not only that, but in The Count of Monte-Cristo, the hero subverts a Chappe telegraph to send a fake message to Paris to undo his nemesis. Sound familiar ?

(although in the original story, the fake message causes a run on the stock exchange, thereby ruining his enemy. And the operator is bribed. Less romantic and much more prosaic than Terry Pratchett's version)

Well, that is what inspired them, seveda! ;-)