1940 - - Broad band carrier systems are introduced allowing for simultaneous calls over a single pair of wires. On October 28th, the first sale of a new stamp honoring Alexander Graham Bell (10 cents) is introduced in Boston.

1941 - - Bell System continues and accelerates defense activities including testing of services for anti-aircraft defense and other military communications. The telephone system of the United States, already carrying 82,000,000 calls per day, sees increases in traffic of 100 to 400 percent when the Japanese attach Pearl Harbor.

1942 - - Bell Telephone Laboratories applies for a patent on an oscillator circuit which almost at once proved of great value in radar systems used in the war. On October 18th, the S.S. Alexander Graham Bell is launched at the Oregon Shipbuilding Corporation yards.

1943 - - First No. 4 toll crossbar switching system in the world goes into service in Philadelphia, PA. The first concrete move toward toll dialing.

1944 - - Bell Telephone Laboratories devotes its facilities to military research and conducts the School for War Training which prepares many men for technical services such as radar maintenance. May 24th marks the Centennial of the Telegraph. Bell System receives National Security Award for measures to protect its telephone plant during the war.

1945 - - Bell Telephone Laboratories continues to devote its facilities to military research as well as conducting the School for War Training. Germany surrenders ending the War in Europe. The Atom Bomb is dropped on Hiroshima and then Nagasaki. Japan surrenders ending the War in the Pacific.

1946 - - First commercial multi-channel high frequency microwave radiotelephone system in Bell System is introduced in southern California as well as between Nantucket (MA) and the mainland. Mobile telephone service placed in commercial use in St. Louis.

1947 - - Appointment of first woman assistant to president in Bell System - Miss Kathryn L. Davenport. On June 19th, the Bell System and Rural Electrification Administration announced development of forms of agreement between telephone companies and REA cooperatives for power line carrier telephone service and joint use of pole lines in rural areas. August 15th sees the introduction (on an experimental basis) of telephone service from moving trains to any other telephone. Mobile Telephone service opened along Boston-Washington highway on September 26th.

1948 - - June 29th marked the installation of the 30,000,000 telephone in the Bell System. On June 30th, the first public demonstration of the transistor by Bell Telephone Laboratories was conducted showing that this device could be used to do the work of some types of vacuum tubes. And the first installation of a No. 5 Crossbar System is completed at Media, PA on July 11th.

1949 - - On January 14th, the U.S. Attorney General filed suit against AT&T Company and Western Electric Company, alleging violation of the Sherman Anti-Trust Act and asking that Western Electric be separated from the Bell System. (Suit was terminated by consent decree, January 24, 1956.) October 17th marked the joining of the toll dialing networks on the east and west coast. Coast-to-coast dialing of long distance calls begins (operator dialing that is). The first sale of gift toll coupon books was attempted during the Christmas season. (Six thousand contacts resulted in 288 sales.) The system call volume reaches 180 million per day.

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