Memo (American Telephone and Telegraph Company, Department of Development and Research), October, 1921, reprinted in Commercial Broadcasting Pioneer: The WEAF Experiment, 1922-1926, William Peck Banning, 1946, page 60:
The technical possibilities of broadcasting from the Bell standpoint may be best indicated by picturing the setup for some national event, such as the Armistice Day ceremonies or the inauguration of the President.
Under such conditions we can imagine the President or other official speaking in Washington with or without the use of local loud speakers, and that his voice is then carried out over a network of wires extending to all the important centers of the country.
If each point on this network can be reached by two or more routes, the possibility of interruption to telephone service would be small. At the offices along the selected route connections are established through one-way repeaters to other circuits, to loud speakers and radio stations, without interfering at all with the main circuit. In each city and larger town there are halls equipped with loud speaking apparatus at which the people in the neighborhood are gathered and which are properly connected directly or indirectly to the backbone routes.
To properly do the above will require that we have available along all of our important routes one or more circuits which are constructed and maintained so as to give a somewhat better grade of transmission, and a somewhat higher degree of reliability.