2 BELL SYSTEM TECHNICAL JOURNAL 



Information is given with respect to international telephone connections 

 in North America, between North America and Europe and other inter- 

 national connections. In covering this subject some of the important 

 items relating to the operation of the transatlantic radio channels are 

 given and reference made to the projected transatlantic telephone cable. 



Various forms of special services closely allied with the message tele- 

 phone service are described. These include telegraph service, telephone 

 circuits provided for private use, foreign exchange service, telephone net- 

 works for program transmission to radio broadcasting stations, electrical 

 transmission of pictures, telephony in connection with aircraft operation, 

 ship to shore telephony, telephony to mobile stations such as railroad 

 trains, telephone services of railroads and other public utilities, telephone 

 public address systems and television. Reference is also made to some 

 of the by-products of the telephone development work which include im- 

 provements in submarine cable telegraphy brought about by the discovery 

 of the alloys known as "permalloy and oerminvar," the development work 

 in the reproduction of sound and in tne talking motion pictures. 



In concluding, the paper points out that careful studies of the future 

 development of the telephone industry indicate a somewhat accelerated 

 rate of development of the services required to meet the demands of the 

 customers and a continuing very rapid technical development of telephone 

 plant and systems to prov-ide the necessary facilities. 



In treating such a large subject in a paper of this kind it has been neces- 

 sary to deal with technical problems in rather general terms and as an 

 attachment to the paper references are made to numerous articles in the 

 technical press for the more technical information. 



General 



THE purpose of this paper is to give a general description of the 

 telephone communication system of the United States of Amer- 

 ica, outlining briefly some of the more important engineering problems 

 involved and indicating the service results obtained. At the begin- 

 ning of this paper it seems important to give a brief description of 

 the general structure and organization of the telephone communica- 

 tion system. 



The commercial telephone system of the United States is entirely 



owned and operated by corporations, partnerships, and individuals. 

 A group of 24 closely associated Bell Telephone Operating Companies 

 owns and operates 14.8 million telephones and the telephone lines 

 used for toll service within their territories. In addition there are 

 in the country about 4.7 million telephones owned by several thousand 

 independent telephone companies which have operating agreements 

 with the Bell Companies providing for the interconnection of lines, 

 thus permitting the operation of 19.5 million telephones as a single 

 system. There are in addition about 140,000 telephones in the coun- 

 try not connected with the Bell System. 



The 24 Bell Operating Companies cover the entire area of the 

 United States and are responsible for all Bell Telephone operations 

 within their respective areas. A number of the larger companies are 

 subdivided into autonomous operating units, there being at the 



