Although famous as a pioneer broadcasting station, Westinghouse's KDKA in East Pittsburgh, Pennsylvania was initially intended to provide point-to-point radiotelegraph communication between the company's operating plants. In fact, its first licence, issued October 27, 1920, doesn't even mention broadcasting to the public, only the inter-plant communication. The company's famous November 2, 1920 election night broadcast was actually sent out under the temporarily assigned Special Amateur callsign of 8ZZ, although after a few days the broadcast service switched to also use the KDKA callsign. And for the first couple of years, KDKA was used both for entertainment broadcasting and point-to-point communication.
Pittsburgh Gazette Times, September 26, 1920, Fifth section, page 10: (Full column at Google newspapers.)
It may be of interest to our readers to learn that a new high-power station, to operate under a special or commercial license, is being installed at the Westinghouse plant in East Pittsburgh. It will be used to establish communication between the East Pittsburgh plant and the company branch factories at Cleveland, O., Newark, N. J., and Springfield, Mass., where similar outfits will be employed. Work on this station has been started, and it is expected to be in operation in about two months' time. While the wave length this station will operate on is not known to us at this time, to those who may imagine all sorts of interference from it we are pleased to advise that there is no need for alarm, because, instead of a spark transmitter, this station will employ a two-kilowatt high-frequency alternator transmitting undamped waves.
October 17, 1920, Eighth section, page 8: (Full column at Google newspapers.)
AN INTERESTING radio development is under way in the Pittsburgh district. A large local concern having branch factories in other cities, the business with which necessitates many telegraph and telephone communications, is planning to try out radio telephony as an economic proposition. It will be realized that with a great deal of inter-branch business the number of telegraph messages and long-distance telephone calls is considerable, amounting up in the course of a year to a substantial sum in toll charges. This sum, it is believed, is more than the cost of operation and maintenance for radio telephone service, which fact has appealed to them, the result being that a radio telephone set is being built for a trial in the near future.
The radiophone will be operated at first as a means of relaying messages from one plant to the other in the following manner: The official employe at one plant having business to transact with some other plant, will call the radio operator by telephone, through the central line exchange at the other plant, giving him the message to be transmitted. The radio operator then transmits the message by radiophone to the radio operator at the other plant, who in turn telephones it, through the local line telephone exchange at that plant to the party to whom it is addressed.
Hope for Direct Method.
It is hoped, however, by the interested parties, that it will ultimately be possible to secure direct communication between parties desiring to converse. To do this it will be necessary to provide intercommunication between the radio transmitting and receiving stations and the local exchanges in the several factories. This, in effect, simply means that the radio modulation is obtained through a telephone transmitter at a distance from the radiophone station, the voice frequently being converted from the desk at which the speaker is located, through his telephone line to the local telephone exchange and then to the local radio equipment where it serves to modulate the radio frequency current being radiated by the radiophone.
This modulated radio frequency current radiated by the wireless phone at the one factory is received by the radiophone operator at the plant with which it is desired to communicate where it is converted into audio frequency current and delivered by the local line telephone exchange there directly to the desired party through the regular line telephone on his desk. In order for this second person to reply to the first, it is only necessary to repeat the operation mentioned originating in this case from the second party's end of the line. In this manner a person in the Pittsburgh plant can talk directly to a second person in another factory, say at Chicago, just the same as has formerly been done by long-distance line telephony, but without as much delay and expense.
It will be realized that such a result is possible only on the solution of a number of troublesome problems, such as interference by other radio stations, static, etc. It is probable, however, that these difficulties can, in a large measure, be overcome and the system will then be of immense value for intercommunication purposes.