Fritz Leiber's "The Creature from Cleveland Depths" aka "The Lone Wolf" (novella, gadgets, free): Who could imagine mobile phones would be so evil?

Well, the story is from long before mobile phones were around, so the gadget (the "tickler") here looks different & works differently.

It begins as an organizer - you tell it to remind you of certain events, & it will at the right time. Reminding is by telling about the event in your ear via an in-ear headphone, plus an insistent "tickling" using two rollers mounted on your shoulder. It runs a very long (audio) magnetic tape - one run lasts a week, with buttons to forward quickly to a certain time. To set an event, you move it specific date/time next week, then speak of the event into it. After you've set the events, the device runs the tape continuously. But most of it is blank, so you don't hear anything till an event is due.

Soon improvements in upgraded versions give it a life all its own, threatening the very human existence...

Very funny early parts & ending, but I thought it was draggy in the middle as the mood begin to set for impending disaster.

Notes.

1. "Depths" of the title has cold war linkage - "Free World" vs Soviet Union. Because of bomb scare most people live in massive underground caverns that double as bomb shelters. Only a few "outers" live on the surface.
2. "Creature" of the title is an advanced form of the tickler gadget.

See also.

1. L Sprague de Camp's "Alanias" (download as part of a larger package): Another story where a voice whispers propaganda into your ear without your conscious self realizing you are being manipulated.

Fact sheet.

First published: Galaxy, December 1962.
Download full text from Project Gutenberg, Manybooks, Feedbooks. [via Becky@ClassicScienceFiction]
Download audio version read by Gregg Margarite from LibriVox.
Alternate audio link at Internet Archive.
Rating: A.
Related: Stories of Fritz Leiber.