Bruce Sterling wrote: "Dead forms of 'hotel annunciator' still await the Necronaut who can resurrect this modest but intimate medium."
You asked for it.
The annunciator, an American invention of the 1830s, was designed to replace the old system of manually ringing bells to summon servants. It was intended for large urban hotels with many rooms, where hand bell ringing would obviously have been impractical.
As it operated in New York's opulent St. Nicholas Hotel, built in 1853, each guest room was equipped with a push button and a dial. The dial's pointer could be turned to read Ice Water, Bellhop, Room Service, etc. Guests turned the dial to the service type desired and pushed the button.
At the front desk, a buzz tone was heard and a metal disc dropped to the bottom of a case filled with discs for all the various rooms. Each disc had a room number and a service type stamped in it, i.e., "MAKE UP 405." The appropriate servant would then be dispatched.
The first annunciators had only one disc per room (and no dials), the guest making the request verbally when a servant arrived. By the 1850s the system had been refined for the even greater convenience of hotel patrons.
Paul Lindemeyer (firstname.lastname@example.org)
CELEBRATING THE SAXOPHONE: An Illustrated History
At your local bookseller from William Morrow & Co.