"Pickman's Modem" by Lawrence Watt-Evans

First appeared in Asimov's.  Reprinted (perhaps the most frequent) by Gardner Dozois, Jim Turner, Sheila Williams, John Gregory Betancourt, and Colin Azariah-Kribbs.

The title indicates it is a play off of H.P. Lovecraft's "Pickman's Model" where the narrator learns that a talented artist on the outs with his artist community because of his grotesque drawing has truly been seeing such visions.

Although the story states it explicitly, Watt-Evans' Pickman is anything but talented.  He'd bought a second-hand Miskatonic Data System modem and it changed his poor grammar/spelling into something more elegant if archaic.  Whereas Pickman tells a person to do something crude, the modem phrases it in a less direct manner.  Pickman is disturbed but not enough to get a new modem....

Maybe you can guess what happens next.  How else can a Cthulhu story end?  This tale gains humor/power when compared to its original.