Here’s an article from the August 1935 issue of Modern Mechanix about a device called the “Notificator”, which sounds a lot like an old-school version of Twitter:
Here’s the text of the article:
To aid persons who wish to make or cancel appointments or inform friends of their whereabouts, a robot message carrier has been introduced in London, England.
Known as the “notificator”, the new machine is installed in streets, stores, railroad stations or other public places where individuals may leave messages for friends.
The user walks up on a small platform in front of the machine, writes a brief message on a continuous strip of paper and drops a coin in the slot. The inscription moves up behind a glass panel where it remains in public view for at least two hours so that the person for whom it is intended may have sufficient time to observe the note at the appointed place. The machine is similar in appearance to a candy-vending device.
[Found via Philip Bond]