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139-745: The laboratory began in the late 19th century as the Western Electric Engineering Department, located at 463 West Street in New York City. After years of conducting research and development under Western Electric , a Bell subsidiary, the Engineering Department was reformed into Bell Telephone Laboratories in 1925 and placed under the shared ownership of Western Electric and the American Telephone and Telegraph Company (AT&T). In

278-545: A CCITT standard. Similar schemes were used in the Americas and in some European countries including Spain. Digit strings between switches were often abbreviated to further improve utilization. For example, one switch might send only the last four or five digits of a telephone number . In one case, seven digit numbers were preceded by a digit 1 or 2 to differentiate between two area codes or office codes, (a two-digit-per-call savings). This improved revenue per trunk and reduced

417-446: A panel switch and a manual switchboard. Probably the most common form of communicating dialed digits between electromechanical switches was sending dial pulses , equivalent to a rotary dial 's pulsing, but sent over trunk circuits between switches. In Bell System trunks, it was common to use 20 pulse-per-second between crossbar switches and crossbar tandems. This was twice the rate of Western Electric/Bell System telephone dials. Using

556-645: A 54% share of the Nippon Electric Company, Ltd. Western Electric's representative in Japan was Walter Tenney Carleton . The company, later known as NEC, would eventually become a major international manufacturer of electronics equipment including semiconductors and personal computers. In 1901, Western Electric secretly purchased a controlling interest in a principal competitor, the Kellogg Switchboard & Supply Company , but in 1909

695-418: A PBX or key telephone system managed by a receptionist, catering to the telecommunication needs of the enterprise. In the era of the electrical telegraph, its principal users were post offices, railway stations, the more important governmental centers (ministries), stock exchanges, very few nationally distributed newspapers, the largest internationally important corporations, and wealthy individuals. Despite

834-664: A Western Electric decision to join Haverhill and Lawrence locations in 1956 as the Merrimack Valley Works. In 1944, Western Electric purchased a factory in St. Paul, Minnesota to restart manufacture of telephone sets for civilian installation as authorized by War Production Board . By 1946, some of these facilities were relocated to the Hawthorne plant as space became available from war-production scale down. Also,

973-459: A central office (C.O.) is a common carrier switching center Class 5 telephone switch in which trunks and local loops are terminated and switched. In the UK, a telephone exchange means an exchange building, and is also the name for a telephone switch. With manual service , the customer lifts the receiver off-hook and asks the operator to connect the call to a requested number. Provided that

1112-484: A circuit connecting a dialed call through an electromechanical switch had DC continuity within the local exchange area via metallic conductors. The design and maintenance procedures of all systems involved methods to avoid that subscribers experienced undue changes in the quality of the service or that they noticed failures. A variety of tools referred to as make-busy s were plugged into electromechanical switch elements upon failure and during repairs. A make-busy identified

1251-412: A digit receiver (part of an element called an Originating Register ) would be connected to a call just long enough to collect the subscriber's dialed digits. Crossbar architecture was more flexible than step offices. Later crossbar systems had punch-card-based trouble reporting systems. By the 1970s, automatic number identification had been retrofitted to nearly all step-by-step and crossbar switches in

1390-586: A factory at that location and the Western Electric company known as W.E. Mfg. Co., at the time, had purchased Western Union's New York Factory to continue the increase of phone production. This site would also place the end to Western Union factories. The Boston shop was located at 109-115 Court Street and it was previously known as the Charles Williams, Jr factory that was purchased by Western Electric in 1882. The consolidation of operations

1529-436: A factory. On August 22, 1952, the facility opened to produce new electronic components for the U.S. government for use by the military and the space program. In the mid-1950s, Western Electric established several more satellite "Shops" that were smaller locations reporting to the larger "Works" locations. The "Montgomery Shops" were occupied in 1955 to produce Data-Phone data sets, wire spring relays, and test sets. Although, it

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1668-517: A failed switch element. A trouble reporting card system was connected to switch common control elements. These trouble reporting systems punctured cardboard cards with a code that logged the nature of a failure. Electromechanical switching systems required sources of electricity in form of direct current (DC), as well as alternating ring current (AC), which were generated on-site with mechanical generators. In addition, telephone switches required adjustment of many mechanical parts. Unlike modern switches,

1807-512: A few outdoor facilities and radio communications development facilities were developed. In 1925, the test plot studies were established at Gulfport, Mississippi , where there were numerous telephone pole samples established for wood preservation. At the Deal, New Jersey location, work was done on ship-to-shore radio telephony. In 1926, in the Whippany section of Hanover Township, New Jersey , land

1946-404: A horizontal panel containing two rows of patch cords, each pair connected to a cord circuit . When a calling party lifted the receiver, the local loop current lit a signal lamp near the jack. The operator responded by inserting the rear cord ( answering cord ) into the subscriber's jack and switched their headset into the circuit to ask, "Number, please?" For a local call, the operator inserted

2085-411: A hundred pair cable between switches, for example. Conductors in one common circuit configuration were named tip, ring, ear (E) and mouth (M). Tip and ring were the voice-carrying pair, and named after the tip and ring on the three conductor cords on the manual operator's console. In two-way trunks with E and M signaling , a handshake took place to prevent both switches from colliding by dialing calls on

2224-485: A lamp on the operator's switchboard, signaling the operator to perform service. In the largest cities, it took many years to convert every office to automatic equipment, such as a panel switch . During this transition period, once numbers were standardized to the 2L-4N or 2L-5N format (two-letter exchange name and either four or five digits), it was possible to dial a number located in a manual exchange and be connected without requesting operator assistance. The policy of

2363-399: A manual office, having listings such as Hillside 834 or East 23, was recognizable by the format in which the second letter was not capitalized. Rural areas, as well as the smallest towns, had manual service and signaling was accomplished with magneto telephones, which had a crank for the signaling generator. To alert the operator, or another subscriber on the same line, the subscriber turned

2502-515: A meeting of the top executives to decide whether I might remain with the Company, for it established a precedent and a new policy for the Company – that of married women in their employ. If the women at the top were permitted to remain after marriage then all women would expect the same privilege. The policy was expanded quickly, so that a few years later women were given maternity leaves with no loss of time on their service records." Western Electric

2641-503: A new building close by at 1537 35th Street N.W., specifically to house the lab. This building was declared a National Historic Landmark in 1972. After the invention of the telephone, Bell maintained a relatively distant role with the Bell System as a whole, but continued to pursue his own personal research interests. The Bell Patent Association was formed by Alexander Graham Bell , Thomas Sanders, and Gardiner Hubbard when filing

2780-588: A new outdoor plant development laboratory. Prior to Chester being established, a test plot was installed in Limon, Colorado in 1929, similar to the one in Gulfport. The three test plots at Gulfport, Limon, and Chester were outdoor facilities for preservatives and prolonging the use of telephone poles. Additionally, in 1929, a land expansion was done at the Deal Labs to 208 acres (84 ha). This added land increased

2919-559: A permanent plant. The 200,000 square-foot leased plant began in June 1971. In 1974, there were 490 IBEW employee members on strike over local agreement issues. In 1975, this San Ramon Valley Plant announced a September 30 closure of its telephone transmission equipment manufacturing operations. On January 27, 1983, the Kearny facility was announced for closure due to technology changes, underutilized, and too costly to maintain. The phase out of

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3058-667: A section chief and one maintenance man. In 1955, the Lawrence plant reached its peak employment at more than 2,000 employees. This Bell Labs research and development satellite had 40 Bell Telephone Laboratories engineers and 25 Western Electric employees. Carrier equipment used filters made with Polystyrene condensers at this Garfield Shops or later referred as Lawrence Shops. In 1952, the Reading plant began when Western Electric converted an old Rosedale knitting mill in Laureldale into

3197-423: A shopping center parking lot, with a remaining two buildings converted. A water tower is the remaining physical association of the industrial research complex where telephones, electronics, military equipment and business management innovations were produced by a facility that once existed. The Baltimore facility closed on February 28, 1986. The facility, which had once employed 6,200, was staffed by 65 employees on

3336-436: A single line. When calling a party, the operator used code ringing, a distinctive ringing signal sequence, such as two long rings followed by one short ring. Everyone on the line could hear the signals, and could pick up and monitor other people's conversations. Automatic exchanges , which provided dial service , were invented by Almon Strowger in 1888. First used commercially in 1892, they did not gain widespread use until

3475-475: A specific geographical region. This region is sometimes known as the exchange area. In North America, the term wire center may be used to denote a central office location, indicating a facility that provides a telephone with a dial tone . Telecommunication carriers also define rate centers for business and billing purposes, which in large cities, might encompass clusters of central offices to specify geographic locations for distance measurement calculations. In

3614-470: A statue originally named Electricity , but later renamed Spirit of Communication , which was raised to the roof of 195 Broadway on October 24, 1916. In 1915, the assets of Western Electric Manufacturing were transferred to a newly incorporated company in New York, New York , named Western Electric Company, Inc , a wholly owned subsidiary of AT&T. The sole reason for the transfer was to provide for

3753-427: A telephone not supplied by the Bell System had to first transfer the phone to the local Bell operating company, who leased the phone back to the customer for a monthly charge in addition to a re-wiring fee. In the 1970s when consumers increasingly bought telephone sets from other manufacturers, AT&T changed the policy for its Design Line telephone series by selling customers the phone housing, retaining ownership of

3892-626: A transmission studies site was established in Phoenixville, Pennsylvania that built, in 1929, the coaxial conductor line for first tests of long-distance transmission in various frequencies. On January 1, 1925, Bell Telephone Laboratories, Inc. was organized to consolidate the development and research activities in the communication field and allied sciences for the Bell System. Ownership was evenly shared between Western Electric and AT&T. The new company had 3600 engineers, scientists, and support staff. Its 400,000-square-foot (37,000 m) space

4031-466: A trunk as idle. Trunk circuitry hearing a 2,600 Hz tone for a certain duration would go idle. (The duration requirement reduced falsing .) Some systems used tone frequencies over 3,000 Hz, particularly on SSB frequency-division multiplex microwave radio relays . On T-carrier binary digital transmission systems, bits within the T-1 data stream were used to transmit supervision. By careful design,

4170-402: A year later. In 1887 Puskás introduced the multiplex switchboard . . Later exchanges consisted of one to several hundred plug boards staffed by switchboard operators . Each operator sat in front of a vertical panel containing banks of ¼-inch tip-ring-sleeve (3-conductor) jacks, each of which was the local termination of a subscriber 's telephone line . In front of the jack panel lay

4309-592: The AT&;T Corporation for most of its lifespan, Western Electric was the primary manufacturer, supplier, and purchasing agent for all telephone equipment for the Bell System from 1881 until 1984, when the Bell System was dismantled . Because the Bell System had a near-total monopoly over telephone service in the United States for much of the 20th century, Western Electric's equipment was widespread across

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4448-880: The Bell Carriage House , the Bell Laboratory and the Volta Laboratory . It focused on the analysis, recording, and transmission of sound. Bell used his considerable profits from the laboratory for further research and education advancing the diffusion of knowledge relating to the deaf. This resulted in the founding of the Volta Bureau ( c.  1887 ) at the Washington, D.C. home of his father, linguist Alexander Melville Bell . The carriage house there, at 1527 35th Street N.W., became their headquarters in 1889. In 1893, Bell constructed

4587-409: The Bell System stated that customers in large cities should not need to be concerned with the type of office, whether they were calling a manual or an automatic office. When a subscriber dialed the number of a manual station, an operator at the destination office answered the call after seeing the number on an indicator , and connected the call by plugging a cord into the outgoing circuit and ringing

4726-737: The Bell Telephone Company in Boston in 1877. The world's first state-administered telephone exchange opened on November 12, 1877 in Friedrichsberg close to Berlin under the direction of Heinrich von Stephan . George W. Coy designed and built the first commercial US telephone exchange which opened in New Haven, Connecticut in January, 1878, and the first telephone booth was built in nearby Bridgeport . The switchboard

4865-569: The Number Five Crossbar Switching System . In 1952, William Gardner Pfann revealed the method of zone melting , which enabled semiconductor purification and level doping. In 1953, Maurice Karnaugh developed the Karnaugh map , used for managing of Boolean algebraic expressions. In January 1954, Bell Labs built one of the first completely transistorized computer machines, TRADIC or Flyable TRADIC, for

5004-649: The Volta Prize of 50,000   francs for the invention of the telephone (equivalent to about US$ 10,000 at the time, or about $ 330,000 now), he used the award to fund the Volta Laboratory (also known as the "Alexander Graham Bell Laboratory") in Washington, D.C. in collaboration with Sumner Tainter and Bell's cousin Chichester Bell . The laboratory was variously known as the Volta Bureau ,

5143-470: The Western Electric 1ESS switch , Northern Telecom SP1 , Ericsson AXE, Automatic Electric EAX-1 & EAX-2, Philips PRX /A, ITT Metaconta, British GPO/BT TXE series and several other designs were similar. Ericsson also developed a fully computerized version of their ARF crossbar exchange called ARE. These used a crossbar switching matrix with a fully computerized control system and provided

5282-607: The Western Electric Manufacturing Company on the Near West Side of Chicago. They manufactured a variety of electrical products including typewriters, alarms, and lighting and had a close relationship with telegraph company Western Union , to whom they supplied relays and other equipment. In 1875, Gray sold his interests to Western Union, including the caveat that he had filed against Alexander Graham Bell 's patent application for

5421-444: The charge-coupled device (CCD), and many other optical, wireless, and wired communications technologies and systems. In 1924, Bell Labs physicist Walter A. Shewhart proposed the control chart as a method to determine when a process was in a state of statistical control. Shewhart's methods were the basis for statistical process control (SPC): the use of statistically based tools and techniques to manage and improve processes. This

5560-546: The crossbar switch . Circuits interconnecting switches are called trunks . Before Signalling System 7 , Bell System electromechanical switches in the United States originally communicated with one another over trunks using a variety of DC voltages and signaling tones. Today, those simple digital signals have been replaced by more modern coded digital signals (typically using binary code). Some signaling communicated dialed digits. An early form called Panel Call Indicator Pulsing used quaternary pulses to set up calls between

5699-415: The telephone when the user removes the handset from the switchhook or cradle. The exchange provides dial tone at that time to indicate to the user that the exchange is ready to receive dialed digits. The pulses or DTMF tones generated by the telephone are processed and a connection is established to the destination telephone within the same exchange or to another distant exchange. The exchange maintains

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5838-583: The telephone . The ensuing legal battle between Western Union and the Bell Telephone Company over patent rights ended in 1879 with Western Union withdrawing from the telephone market and Bell acquiring Western Electric in 1881. This purchase was a crucial step in standardizing telephone instruments and concentrating manufacturing in a single entity. In the company's first few years as Western Electric, there were five manufacturing locations located at Chicago (220-232 Kinzie St.) New York, Boston, Indianapolis and Antwerp, Belgium. The locations were not permanent, as

5977-402: The thermal noise in a resistor was first measured by John B. Johnson , for which Harry Nyquist provided the theoretical analysis; this is now termed Johnson-Nyquist noise . During the 1920s, the one-time pad cipher was invented by Gilbert Vernam and Joseph Mauborgne at the laboratories. Bell Labs' Claude Shannon later proved that it is unbreakable. In 1928, Harold Black invented

6116-551: The 1920s. In 1923, construction began on the second factory located in Kearny, New Jersey . The location was known as Kearny Works and in 1925 began telephone cable production. On June 15, 1928, Western Electric employees, photographed by Rosenfeld and Sons, were pictured, in a groundbreaking ceremony , for their expansion of the Kearny Works manufacturing facility at 110 Central Ave, Kearny, New Jersey. Kearny Works would achieve

6255-480: The 1940s, the Bell System in the United States and Canada introduced a nationwide numbering system that identified central offices with a unique three-digit code, along with a three-digit numbering plan area code (NPA code or area code), making central office codes distinctive within each numbering plan area. These codes served as prefixes in subscriber telephone numbers. The mid-20th century saw similar organizational efforts in telephone networks globally, propelled by

6394-399: The 1960s, laboratory and company headquarters were moved to Murray Hill, New Jersey . Its alumni during this time include people like William Shockley , Dennis Ritchie , Claude Shannon and Willard Boyle . Bell Labs became a subsidiary of AT&T Technologies in 1984 after the Bell System was broken up . After the breakup, its funding greatly declined. In 1996, AT&T Technologies

6533-655: The Allies in World War II . The British wartime codebreaker Alan Turing visited the labs at this time, working on speech encryption and meeting Claude Shannon . Bell Labs Quality Assurance Department gave the world and the United States such statisticians as Walter A. Shewhart , W. Edwards Deming , Harold F. Dodge , George D. Edwards , Harry Romig, R. L. Jones, Paul Olmstead, E.G.D. Paterson, and Mary N. Torrey . During World War II, Emergency Technical Committee – Quality Control, drawn mainly from Bell Labs' statisticians,

6672-452: The Bell System by 1889. American Bell held a controlling interest in Western Electric (which was the manufacturing arm of the business) whereas AT&T was doing research into the service providers. In 1896, Western Electric bought property at 463 West Street to centralize the manufacturers and engineers which had been supplying AT&T with such technology as telephones, telephone exchange switches and transmission equipment. During

6811-409: The Bell System required continuous maintenance, such as cleaning. Indicator lights on equipment bays alerted staff to conditions such as blown fuses (usually white lamps) or a permanent signal (stuck off-hook condition, usually green indicators). Step offices were more susceptible to single-point failures than newer technologies. Crossbar offices used more shared, common control circuits. For example,

6950-414: The Bell System. Electronic switching systems gradually evolved in stages from electromechanical hybrids with stored program control to the fully digital systems. Early systems used reed relay -switched metallic paths under digital control. Equipment testing, phone numbers reassignments, circuit lockouts and similar tasks were accomplished by data entry on a terminal. Examples of these systems included

7089-474: The Strowger's typical 10 pps—typically about 20 pps. At a later date many also accepted DTMF "touch tones" or other tone signaling systems. A transitional technology (from pulse to DTMF) had converters to convert DTMF to pulse, to feed to older Strowger, panel, or crossbar switches. This technology was used as late as mid-2002. Many terms used in telecommunication technology differ in meaning and usage among

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7228-505: The United States Air Force with 10,358 germanium point-contact diodes and 684 Bell Labs Type 1734 Type A cartridge transistors. The design team was led by electrical engineer Jean Howard Felker with James R. Harris and Louis C. Brown ("Charlie Brown") as the lead engineers on the project, which started in 1951. The device took only 3 cubic-feet and consumed 100 watt power for its small and low powered design in comparison to

7367-612: The Voder being demonstrated at the 1939 New York World's Fair. Bell researcher Clinton Davisson shared the Nobel Prize in Physics with George Paget Thomson for the discovery of electron diffraction , which helped lay the foundation for solid-state electronics . In the early 1940s, the photovoltaic cell was developed by Russell Ohl . In 1943, Bell developed SIGSALY , the first digital scrambled speech transmission system, used by

7506-459: The Western Electric brand. Early on, Western Electric also managed an electrical equipment distribution business, furnishing its customers with non-telephone products made by other manufacturers This electrical distribution business was spun off from Western Electric in 1925 and organized into a separate company, Graybar Electric Company , in honor of the company's founders, Elisha Gray and Enos Barton. Bell Telephone Laboratories , created from

7645-780: The Whippany site was purchased by Bayer ). The largest grouping of people in the company was in Illinois , at Naperville - Lisle , in the Chicago area, which had the largest concentration of employees (about 11,000) prior to 2001. There also were groups of employees in Indianapolis , Indiana; Columbus, Ohio ; North Andover, Massachusetts ; Allentown, Pennsylvania ; Reading, Pennsylvania ; and Breinigsville, Pennsylvania ; Burlington, North Carolina (1950s–1970s, moved to Greensboro 1980s) and Westminster, Colorado . Since 2001, many of

7784-440: The advent of international and transoceanic telephone trunks and direct customer dialing. For corporate or enterprise applications, a private telephone exchange is termed a private branch exchange (PBX), which connects to the public switched telephone network. A PBX serves an organization's telephones and any private leased line circuits, typically situated in large office spaces or organizational campuses. Smaller setups might use

7923-471: The appropriated bits did not change voice quality appreciably. Robbed bits were translated to changes in contact states (opens and closures) by electronics in the channel bank hardware. This allowed direct current E and M signaling, or dial pulses, to be sent between electromechanical switches over a pure digital carrier which did not have DC continuity. Bell System installations typically had alarm bells, gongs, or chimes to announce alarms calling attention to

8062-407: The automation of telephone circuit switching. While there were many extensions and adaptations of this initial patent, the one best known consists of 10 levels or banks, each having 10 contacts arranged in a semicircle. When used with a rotary telephone dial , each pair of digits caused the shaft of the central contact "hand" of the stepping switch to first step (ratchet) up one level for each pulse in

8201-474: The call only if intermediate trunk lines were available between all the centers at the same time. In 1943 when military calls had priority, a cross-country US call might take as long as 2 hours to request and schedule in cities that used manual switchboards for toll calls. On March 10, 1891, Almon Brown Strowger , an undertaker in Kansas City, Missouri , patented the stepping switch , a device which led to

8340-606: The center of the galaxy . In 1931 and 1932, the labs made experimental high fidelity, long playing, and even stereophonic recordings of the Philadelphia Orchestra , conducted by Leopold Stokowski . In 1933, stereo signals were transmitted live from Philadelphia to Washington, D.C. In 1937, the vocoder , an electronic speech compression device, or codec, and the Voder , the first electronic speech synthesizer , were developed and demonstrated by Homer Dudley ,

8479-437: The circuit, allowing them to handle another call, while the caller heard an audible ringback signal, so that that operator would not have to periodically report that they were continuing to ring the line. In the ringdown method, the originating operator called another intermediate operator who would call the called subscriber, or passed it on to another intermediate operator. This chain of intermediate operators could complete

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8618-421: The closure date. By the time AT&T was dissolved in the early 1980s, more than twenty production plants around the country ("Works" locations) had been established. Telephone exchange A telephone exchange , also known as a telephone switch or central office , is a crucial component in the public switched telephone network (PSTN) or large enterprise telecommunications systems. It facilitates

8757-419: The connection until one of the parties hangs up. This monitoring of connection status is called supervision. Additional features, such as billing equipment, may also be incorporated into the exchange. The Bell System dial service implemented a feature called automatic number identification (ANI) which facilitated services like automated billing, toll-free 800-numbers , and 9-1-1 service. In manual service,

8896-406: The construction of Hawthorne Works first buildings were authorized by Barton. In 1907, the research and development staffs of Western Electric and AT&T were consolidated to 463 West Street, New York. The location served the newly Western Electric Engineering Department for the responsibility of the testing and inspection of its telephones and equipment. AT&T's Engineering Department retained

9035-554: The country. The company was responsible for many technological innovations, as well as developments in industrial management. In 1856, George Shawk, a craftsman and telegraph maker, purchased an electrical engineering business in Cleveland, Ohio . In January 1869, Shawk had partnered with Enos M. Barton in the former Western Union repair shop of Cleveland, to manufacture burglar alarms, fire alarms, and other electrical items. Both men were former Western Union employees. Shawk,

9174-581: The crank to generate ringing current. The switchboard responded by interrupting the circuit, which dropped a metal tab above the subscriber's line jack and sounded a buzzer. Dry cell batteries, normally two large N°. 6 cells in the subscriber's telephone, provided the direct current for the transmitter. Such magneto systems were in use in the US as late as 1983, as in the small town, Bryant Pond, Woodstock, Maine . Many small town magneto systems featured party lines , anywhere from two to ten or more subscribers sharing

9313-533: The decade. Shannon was also the founder of modern cryptography with his 1949 paper Communication Theory of Secrecy Systems . The 1950s also saw developments based upon information theory . The central development was binary code systems. Efforts concentrated on the prime mission of supporting the Bell System with engineering advances, including the N-carrier system, TD microwave radio relay , direct distance dialing , E- repeater , wire spring relay , and

9452-468: The destination station. For example, if a dial customer calling from TAylor 4725 dialed a number served by a manual exchange, e.g., ADams 1383-W, the call was completed, from the subscriber's perspective, exactly as a call to LEnnox 5813, in an automated exchange. The party line letters W, R, J, and M were only used in manual exchanges with jack-per-line party lines. In contrast to the listing format MAin 1234 for an automated office with two capital letters,

9591-615: The early 20th century, several historically significant laboratories were established. In 1915, the first radio transmissions were made from a shack in Montauk, Long Island . That same year, tests were performed on the first transoceanic radio telephone at a house in Arlington County, Virginia . A radio reception laboratory was established in 1919 in the Cliffwood section of Aberdeen Township, New Jersey . Additionally for 1919,

9730-494: The engineering department of Western Electric in 1925, was half-owned by Western Electric, the other half belonging to AT&T. The company began to increase its presence in other sectors of industry for new products. In September 1931, the Teletype Corporation headquartered in Chicago on Wrightwood Ave, became a subsidiary of Western Electric and it was a manufacturer of teletypewriters for TWX services. There

9869-455: The facility for radio transmission studies. The beginning of 1930s, established three facilities with radio communications experiments and chemical aspects testing. By 1939, the Summit, New Jersey , chemical laboratory was nearly 10 years established in a three-story building conducted experiments in corrosion, using various fungicides tests on cables, metallic components, or wood. For 1929, land

10008-448: The facility jobs started in fall of 1983 and the 59 year old, 3 million-square-foot, 144-acre facility was sold officially on May 21, 1984, with nearly 1000 last employees left at the plant. The former facility was purchased and later existed as warehouses, distribution, research and light manufacturing facilities. As modern facilities around the country were used for the operations of Hawthorne and its productions distributed, announcement

10147-409: The fact that telephone devices existed before the invention of the telephone exchange, their success and economical operation would have been impossible on the same schema and structure of the contemporary telegraph, as prior to the invention of the telephone exchange switchboard, early telephones were hardwired to and communicated with only a single other telephone (such as from an individual's home to

10286-493: The faster pulsing rate made trunk utilization more efficient because the switch spent half as long listening to digits. DTMF was not used for trunk signaling. Multi-frequency (MF) was the last of the pre-computerized methods. It used a different set of tones sent in pairs like DTMF. Dialing was preceded by a special keypulse (KP) signal and followed by a start (ST). Variations of the Bell System MF tone scheme became

10425-572: The first transatlantic communications cable to carry telephone conversations, was laid between Scotland and Newfoundland in a joint effort by AT&T, Bell Laboratories, and British and Canadian telephone companies. In 1957, Max Mathews created MUSIC , one of the first computer programs to play electronic music . Robert C. Prim and Joseph Kruskal developed new greedy algorithms that revolutionized computer network design . In 1957 Frosch and Derick, using masking and predeposition, were able to manufacture silicon dioxide field effect transistors;

10564-435: The first decade of the 20th century. They eliminated the need for human switchboard operators who completed the connections required for a telephone call . Automation replaced human operators with electromechanical systems, and telephones were equipped with a dial by which a caller transmitted the destination telephone number to the automatic switching system. A telephone exchange automatically senses an off-hook condition of

10703-424: The first digit and then to swing horizontally in a contact row with one small rotation for each pulse in the next digit. Later stepping switches were arranged in banks, the first stage of which was a linefinder . If one of up to a hundred subscriber lines (two hundred lines in later linefinders) had the receiver lifted "off hook", a linefinder connected the subscriber's line to a free first selector, which returned

10842-763: The first patents for the telephone in 1876. Bell Telephone Company, the first telephone company, was formed a year later. It later became a part of the American Bell Telephone Company. In 1884, the American Bell Telephone Company created the Mechanical Department from the Electrical and Patent Department formed a year earlier. American Telephone & Telegraph Company (AT&T) and its own subsidiary company took control of American Bell and

10981-497: The first planar transistors, in which drain and source were adjacent at the same surface. They showed that silicon dioxide insulated, protected silicon wafers and prevented dopants from diffusing into the wafer. In 1958, a technical paper by Arthur Schawlow and Charles Hard Townes first described the laser . Western Electric Western Electric Co., Inc. was an American electrical engineering and manufacturing company that operated from 1869 to 1996. A subsidiary of

11120-433: The former locations have been scaled down or closed. Bell's Holmdel research and development lab , a 1,900,000-square-foot (180,000 m) structure set on 473 acres (191 ha), was closed in 2007. The mirrored-glass building was designed by Eero Saarinen . In August 2013, Somerset Development bought the building, intending to redevelop it into a mixed commercial and residential project. A 2012 article expressed doubt on

11259-399: The front cord of the pair ( ringing cord ) into the called party's local jack and started the ringing cycle. For a long-distance call, the operator plugged into a trunk circuit to connect to another operator in another bank of boards or at a remote central office. In 1918, the average time to complete the connection for a long-distance call was 15 minutes. Early manual switchboards required

11398-492: The headquarters in Chicago had moved to a new building on Clinton Street, the New York shop had moved two city blocks to a new building on Greenwich Street, and both Boston and Indianapolis factories closed. The Antwerp location was at the same location under Western Electric operations until sold in 1925 to ITT. In April 1879, the New York shop was located at 62-68 New Church Street, Lower Manhattan, New York. Western Union had

11537-613: The high volume of manufacturing products. The North Carolina Works was located in Winston-Salem, North Carolina. The Merrimack Valley Works location was in North Andover, Massachusetts . The Kansas City Works location was in Lee's Summit, Missouri . A Lawrence, Massachusetts factory opened on November 13, 1951, and was called the "Garfield Shops." The location started with as a wired units job and there were thirteen workers with

11676-404: The impetus for the creation of a new industrial sector. As with the invention of the telephone itself, the honour of "first telephone exchange" has several claimants. One of the first to propose a telephone exchange was Hungarian Tivadar Puskás in 1877 while he was working for Thomas Edison . The first experimental telephone exchange was based on the ideas of Puskás, and it was built by

11815-474: The interconnection of telephone subscriber lines or digital system virtual circuits, enabling telephone calls between subscribers. The terminology used in telecommunications has evolved over time, with telephone exchange and central office often used interchangeably, the latter term originating from the Bell System . A central office typically refers to a facility that houses the inside plant equipment for one or several telephone exchanges, each catering to

11954-491: The internal mechanical and electrical components, which still required paying AT&T a monthly leasing fee. Starting in 1983 with the breakup of the Bell System, Western Electric telephones could be sold to the public under the brand name American Bell, a newly created subsidiary of AT&T. One of the terms of the Modification of Final Judgment in the Bell System divestiture procedures prohibited AT&T from using

12093-444: The issuance of a non-voting preferred class of capital stock, disallowed under the statutes of the state of Illinois. In the Bell System, telephones were leased by the operating companies to subscribers, and remained the property of the Bell System. Service subscribers paid a monthly fee included in the service charge, while paying additionally for special types or features of telephones, such as colored telephone sets. Equipment repair

12232-581: The largest square foot size of 3,579,000 throughout the years and be the second largest plant for Western Electric manufacturing plants built before the 1930s, only second in size to the Hawthorne Works at Cicero, Illinois . Here is an aerial image of Kearny Works, between 1925 and 1930, held in the Library Company of Philadelphia. with the picture of the entire plant and railways. In 1929, work began at Point Breeze, Baltimore, Maryland as

12371-616: The later Bell Laboratories locations in New Jersey were Holmdel Township , Crawford Hill , the Deal Test Site , Freehold , Lincroft , Long Branch , Middletown , Neptune Township , Princeton , Piscataway , Red Bank , Chester Township , and Whippany . Of these, Murray Hill and Crawford Hill remain in existence (the Piscataway and Red Bank locations were transferred to and are now operated by Telcordia Technologies and

12510-400: The location performed precision frequency-measuring apparatus, field strength measurements, and conducted radio interference. By the early 1940s, Bell Labs engineers and scientists had begun to move to other locations away from the congestion and environmental distractions of New York City, and in 1967 Bell Laboratories headquarters was officially relocated to Murray Hill, New Jersey . Among

12649-560: The name Bell after January 1, 1984; prior to this, AT&T's plan was to market products and services under the American Bell name, accompanied by the now familiar AT&T globe logo. In 1903, Western Electric began construction of the first buildings for Hawthorne Works on the outskirts of Chicago . In 1905, the Clinton Street power apparatus shops moved to Hawthorne. Further expansion of large factories began in

12788-487: The negative feedback system commonly used in amplifiers. Later, Harry Nyquist analyzed Black's design rule for negative feedback. This work was published in 1932 and became known as the Nyquist criterion . In 1931, a foundation for radio astronomy was laid by Karl Jansky during his work investigating the origins of static on long-distance shortwave communications . He discovered that radio waves were being emitted from

12927-399: The number is in the same central office, and located on the operator's switchboard, the operator connects the call by plugging the ringing cord into the jack corresponding to the called customer's line. If the called party's line is on a different switchboard in the same office, or in a different central office, the operator plugs into the trunk for the destination switchboard or office and asks

13066-476: The number of digit receivers needed in a switch. Every task in electromechanical switches was done in big metallic pieces of hardware. Every fractional second cut off of call set up time meant fewer racks of equipment to handle call traffic. Examples of signals communicating supervision or call progress include E and M signaling , SF signaling, and robbed-bit signaling. In physical (not carrier) E and M trunk circuits, trunks were four wire. Fifty trunks would require

13205-479: The operations for pulp cable relocated to Phoenix Works. A loss of 400 positions were expected eliminated in the process. After the Bell System breakup, Western Electric facilities were known as AT&T Technologies facilities in 1984. The three largest and oldest facilities, Hawthorne Works, Kearny Works, and Baltimore Works were closed shortly after due to "excess space". Western Electric used various logos during its existence. Starting in 1914 it used an image of

13344-432: The operator answering (known as the "B" operator) to connect the call. Most urban exchanges provided common-battery service, meaning that the central office provided power to the subscriber telephone circuits for operation of the transmitter, as well as for automatic signaling with rotary dials . In common-battery systems, the pair of wires from a subscriber's telephone to the exchange carry 48V (nominal) DC potential from

13483-543: The operator knows where a call is originating by the light on the switchboard jack field. Before ANI, long-distance calls were placed into an operator queue and the operator asked the calling party's number and recorded it on a paper toll ticket. Early exchanges were electromechanical systems using motors, shaft drives, rotating switches and relays . Some types of automatic exchanges were the Strowger switch or step-by-step switch, All Relay, panel switch , Rotary system and

13622-408: The operator to operate listening keys and ringing keys, but by the late 1910s and 1920s, advances in switchboard technology led to features which allowed the call to be automatically answered immediately as the operator inserted the answering cord, and ringing would automatically begin as soon as the operator inserted the ringing cord into the called party's jack. The operator would be disconnected from

13761-427: The part being worked on as in-use, causing the switching logic to route around it. A similar tool was called a TD tool. Delinquent subscribers had their service temporarily denied (TDed). This was effected by plugging a tool into the subscriber's office equipment on Crossbar systems or line group in step-by-step switches. The subscriber could receive calls but could not dial out. Strowger-based, step-by-step offices in

13900-426: The person's business ). A telephone exchange is a telephone system for a small geographic area that provides the switching (interconnection) of subscriber lines for calls made between them. Telephone exchanges replaced small telephone systems that connected its users with direct lines between each and every subscriber station. Exchanges made telephony an available and comfortable technology for everyday use and it gave

14039-612: The reduced production of home telephones because of the war, began to have a backlog of two million orders in late 1945 for the Hawthorne plant. Western Electric had acquired a former Studebaker plant on Archer Avenue (Chicago, Illinois) for assemblers that produced out one hundred thousand Model 302s telephones by March 1946. After World War II, the National Carbon Company left a facility that had manufactured United States Navy submarine batteries and underwater detonators in Winston-Salem. This facility at 800 Chatham Road,

14178-459: The responsibility for the growth of the Bell System with compatible equipment and service. Gradually the consolidation improved and advanced the telephony response to expanding use. On July 24, 1915, employees of the Hawthorne Works boarded the SS Eastland in downtown Chicago for a company picnic. The ship rolled over at the dock and over 800 people died. In 1920, Alice Heacock Seidel

14317-509: The result was not published until 1950. In 1948, " A Mathematical Theory of Communication ", one of the founding works in information theory , was published by Claude Shannon in the Bell System Technical Journal . It built in part on earlier work in the field by Bell researchers Harry Nyquist and Ralph Hartley , but went much further. Bell Labs also introduced a series of increasingly complex calculators through

14456-414: The same trunk at the same time. By changing the state of these leads from ground to −48 volts, the switches stepped through a handshake protocol. Using DC voltage changes, the local switch would send a signal to get ready for a call and the remote switch would reply with an acknowledgment (a wink) to go ahead with dial pulsing. This was done with relay logic and discrete electronics. These voltage changes on

14595-457: The subscriber a dial tone to show that it was ready to receive dialled digits. The subscriber's dial pulsed at about 10 pulses per second, although the speed depended on the standard of the particular telephone administration. Exchanges based on the Strowger switch were eventually challenged by other exchange types and later by crossbar technology. These exchange designs promised faster switching and would accept inter-switch pulses faster than

14734-460: The success of the newly named Bell Works site, but several large tenants had announced plans to move in through 2016 and 2017. Bell Lab's 1974 corporate directory listed 22 labs in the United States, located in: Nokia Bell Lab's 2024 website pictured 10 labs, located in: Also listed as research locations without additional information was Sunnyvale, California , US and Tampere, Finland . The Naperville, Illinois Bell Labs location near Chicago

14873-400: The telephone company end across the conductors. The telephone presents an open circuit when it is on-hook or idle. When a subscriber's phone is off-hook, it presents an electrical resistance across the line which causes current to flow through the telephone and wires to the central office. In a manually operated switchboard, this current flowed through a relay coil, and actuated a buzzer or

15012-464: The third manufacturing location, Baltimore Works, began its occupancy by 1930 for various cable and wire production. Two manufacturing plants in Lincoln, Nebraska were leased in 1943 to Western Electric to manufacture signal corps equipment and later production demands from Hawthorne Works. The Eighth Street building, known as "Lincoln Shops," and the 13th Street building were the locations, the latter

15151-539: The three oldest manufacturing facilities for product manufacturing transfers and employee expected layoffs. The Kearny Works facility that made systems to convert commercial power to run various telecom equipment, would transfer remaining work to Dallas Works. The shutdown of the plant would eliminate 4,000 jobs. The Baltimore Works facility that made connectors and protectors for wire and cable had work moved to Omaha Works. A total of 2,300 jobs were potentially eliminated after that announcement. The Hawthorne Works facility, had

15290-434: The trunk circuit would cause pops or clicks that were audible to the subscriber as the electrical handshaking stepped through its protocol. Another handshake, to start timing for billing purposes, caused a second set of clunks when the called party answered. A second common form of signaling for supervision was called single-frequency or SF signaling . The most common form of this used a steady 2,600 Hz tone to identify

15429-468: The vacuum tube designs of the times. The device could be installed in a B-52 Stratofortress Bomber and had a performance up to one million logical operations a second. The flyable program used a Mylar sheet with punched holes, instead of the removable plugboard. In 1954, the first modern solar cell was invented at Bell Laboratories. In 1955, Carl Frosch and Lincoln Derick discovered semiconductor surface passivation by silicon dioxide. In 1956 TAT-1 ,

15568-519: The variety of new designs introduced into the market place. This led Western Electric to pursue extreme reliability and durability in design to minimize service calls. In particular, the work of Walter A. Shewhart , who developed new techniques for statistical quality control in the 1920s, helped lead to the quality of manufacture of Western Electric telephones. AT&T also strictly enforced policies against using telephone equipment by other manufacturers on their network. A customer who insisted on using

15707-451: The various English speaking regions. For the purpose of this article the following definitions are made: A central office originally was a primary exchange in a city with other exchanges service parts of the area. The term became to mean any switching system including its facilities and operators. It is also used generally for the building that houses switching and related inside plant equipment. In United States telecommunication jargon,

15846-568: Was acquired and established for the development of a 50-kilowatt broadcast transmitter. In 1931, Whippany increased with 75 acres (30 ha) added from a nearby property. In 1928, a 15-acre (6.1 ha) site in Chester Township, New Jersey , was leased for outdoor tests, though the facility became inadequate for such purposes. In 1930, the Chester location required the purchase of an additional 85 acres (34 ha) of land to be used for

15985-668: Was agreed on September 3, 1974, with employees at 13 plants returning to work. Only the company's subsidiary Teletype Corporation plant in Little Rock, Arkansas and two plants, the Columbia River Switching Equipment factory in Vancouver, Washington and in San Ramon, California were subject to ratification or in negotiations to settle local agreements. In 1983, corporate announcements were made at

16124-593: Was built from "carriage bolts, handles from teapot lids and bustle wire" and could handle two simultaneous conversations. Charles Glidden is also credited with establishing an exchange in Lowell, MA. with 50 subscribers in 1878. In Europe other early telephone exchanges were based in London and Manchester , both of which opened under Bell patents in 1879. Belgium had its first International Bell exchange (in Antwerp )

16263-703: Was called "Buffalo Plant." A satellite shop was established in Jersey City, New Jersey called "Marion Shops" and occupied in 1947. This location produced portable test sets, rectifiers, and power equipment for the main plant known as the Kearny Works. In July 1948, the equipment plant at Duluth, Minnesota was involved in the National Labors Act with bargaining units of IAM and IBEW. After 1947, eight Works locations were built and occupied by 1961 at Allentown, Indianapolis, North Carolina, Merrimack Valley, Omaha, Columbus, Oklahoma City, and Kansas City for

16402-505: Was considered the Chicago Innovation Center and hosted Nokia's second annual Algorithm World event in 2022. Bell Laboratories was, and is, regarded by many as the premier research facility of its type, developing a wide range of revolutionary technologies, including radio astronomy , the transistor , the laser , information theory , the operating system Unix , the programming languages C and C++ , solar cells ,

16541-621: Was done in 1884 to Chicago and New York factories by Charles Williams becoming a Western Electric Manager. In 1888–1889, Western Electric built a 10-story factory building at 125 Greenwich Street in Lower Manhattan, to manufacture some of the first telephones. The New York shop that was renting the Western Union building moved to this building. In preparation for the Chicago Worlds Fair of 1892, Western Electric

16680-411: Was expanded with a new building occupying about one quarter of a city block. The first chairman of the board of directors was John J. Carty , AT&T's vice president, and the first president was Frank B. Jewett , also a board member, who stayed there until 1940. The operations were directed by E. B. Craft, executive vice-president, and formerly chief engineer at Western Electric. In the early 1920s,

16819-606: Was expanding beyond making telephone equipment and American Bell noticed its division from a manufacturing business to a supply business. Western Electric decided to split in 1921, the supply department from the manufacturing business and this led later to a separate entity. In 1925, ITT purchased the Bell Telephone Manufacturing Company of Brussels, Belgium, and other worldwide subsidiaries from AT&T, to avoid an antitrust action. The company manufactured rotary system switching equipment under

16958-504: Was forced by a lawsuit to sell back to Milo Kellogg. The Manufacturers Junction Railway Company was incorporated in January 1903 to provide rail connections to major railroad systems. There were approximately 13 miles of track in and out of Hawthorne Works for rail freight of inbound materials and outbound finished products. Western Electric had a tenure of 50 years up to 1952, in the responsibility and operation of its use for Hawthorne and other nearby industrial companies. Also, in 1903,

17097-576: Was included in the fees. This system had the effect of subsidizing basic telephone service, keeping local telephone service inexpensive, under $ 10 per month. After divestiture, basic service prices increased, and customers became responsible for inside building wiring and telephone equipment. The Bell System had an extensive policy and infrastructure to recycle or refurbish equipment taken out of service, replacing all defective, weak, or otherwise unusable parts for new installations. This resulted in extraordinary longevity of Western Electric telephones, and limited

17236-460: Was instrumental in advancing Army and Navy ammunition acceptance and material sampling procedures. In 1947, the transistor , arguably the most important invention developed by Bell Laboratories, was invented by John Bardeen , Walter Houser Brattain , and William Bradford Shockley (who subsequently shared the Nobel Prize in Physics in 1956). In 1947, Richard Hamming invented Hamming codes for error detection and correction . For patent reasons,

17375-538: Was interested in leading a manufacturing plant capable of long-term developments. Shawk found those plans were beyond his business goals and offered to sell his half-interest partnership to Gray. Anson Stager , a former Chief of the U.S. Military Telegraphs during the American Civil War , advanced money for Gray to buy the half-interest and become a partner when Gray and Barton moved operations to Chicago . Gray and Barton previously knew Stager and an agreement

17514-612: Was located in Montgomery, Illinois, it reported and supported production of the main plant, Hawthorne Works in Cicero, Illinois. The Kearny Works facility had satellite shops that were apart from its location but were part of the manufacturing process. Located in Fair Lawn, New Jersey and occupied since 1956, the "Fair Lawn Shops" produced coils, resistors, transformers, and keys under Kearny manufacturing. The Indianapolis Works facility

17653-611: Was made on June 24, 1983, for closure. Between 1975 and 1983, the Foundry and most of the Telephone Apparatus buildings were demolished and in 1986–1987, the remaining Telephone Apparatus buildings and the Executive Tower were demolished. The Hawthorne facility was in operations for 83 years when it closed its doors in 1986 and torn down for a shopping center. Another building was demolished on April 10, 1994, for

17792-441: Was passed to Western Electric Company and operated until 1966 for production of national telephone companies' switches and circuits. Additionally, the location complex was one of three nationwide Western Electric field engineering sites. The mid-1940s brought occupancy to locations. A plant was established in 1946 at Tonawanda, New York to produce equipment wiring cable, telephone cords, enamelled wire, and insulated wire. This plant

17931-477: Was producing telephone sets and components with a satellite shop. The Indianapolis shop known as "Washington Street Shop" produced miscellaneous subscriber apparatus since its occupancy in 1957. The "Lawrence Shop" that was occupied in 1957 produced BELLBoy receivers, telephone repeaters and carrier products under Merrimack Valley Works. The "Clark Shop" was occupied in 1959 at Clark, New Jersey and manufactured submarine cable repeaters and components. The satellite shop

18070-818: Was purchased in Holmdel Township, New Jersey , for a radio reception laboratory to replace the Cliffwood location that had been in operation since 1919. In 1930, the Cliffwood location was ending its operations as Holmdel was established. Whereas, in 1930, a location in Mendham Township, New Jersey , was established to continue radio receiver developments farther from the Whippany location and eliminate transmitter interference at that facility with developments. The Mendham location worked on communication equipment and broadcast receivers. These devices were used for marine, aircraft, and police services as well as

18209-419: Was responsible for the organized Bell System sales activities and merchandising of apparatus for the 900 long-distance circuit from New York to Chicago. In 1897, the building at 463 West Street, New York was constructed and housed the New York shop as well as the company Eastern headquarters. Western Electric was the first company to join in a Japanese joint venture with foreign capital. In 1899, it invested in

18348-410: Was signed on November 18, 1869, to launch the company as Gray & Barton. The firm was open for business by the end of the year in Chicago. In December 1869, the location was at 162 South Water Street in Chicago. On December 31, 1869, he entered a partnership with Barton, and later sold his share to inventor Gray. In 1872, Barton and Gray moved the business to Clinton Street, and incorporated it as

18487-488: Was sold in 1950 for $ 500,000 to Western Electric. The plants were closed after the Omaha Works opened in 1958. Western Electric acquired in 1943, the old Grad and Winchell buildings located at Haverhill, Massachusetts. New Jersey supervisors taught former textile and shoe workers the manufacturing process of coil winding. The employees' acquired skills demonstrated their versatility in this new manufacturing process for

18626-530: Was spun off and renamed to Lucent Technologies, who used the Murray Hill site as their headquarters. Bell Laboratories was split as well, with part of it going to AT&T as AT&T Laboratories . In 2006, Lucent merged with French telecommunications company Alcatel to form Alcatel-Lucent , which was in turn acquired by Nokia in 2016. In 1880, when the French government awarded Alexander Graham Bell

18765-526: Was the Cleveland shop foreman and Barton, was a Rochester, New York telegrapher. During this Shawk and Barton partnership, one customer was an inventor sourcing parts and models for experiments. That inventor was Elisha Gray , a former physics professor at Oberlin College . Barton thought of future growth in electrical apparatus potential for the company and shared a common enthusiasm with the inventor, who

18904-843: Was the acquisition in 1931 of the Nassau Smelting and Refining plant located in Totenville, Staten Island, New York to recycle Bell System scrap wire, metal, and becoming a subsidiary of Western Electric. The acquisition of the Queensboro factory in Middle Village, New York became a Western Electric Shop in the 1930s to produce wooden telephone booths. In 1974, the IBEW members at Western Electric's 16 plants went on strike over improved benefits, cost‐of‐living adjustments, and pay increase for up to three years. The ratified contract

19043-432: Was the first female Western Electric employee to be given permission to stay on after she had married. This set a precedent in the company, which previously had not allowed married women in their employ. Miss Heacock had worked for Western Electric for sixteen years before her marriage, and was at the time the highest-paid secretary in the company. In her memoirs, she wrote that the decision to allow her to stay on "required

19182-426: Was the origin of the modern quality control movement, including Six Sigma . In 1926, the laboratories invented an early synchronous-sound motion picture system, in competition with Fox Movietone and DeForest Phonofilm . In 1927, a Bell team headed by Herbert E. Ives successfully transmitted long-distance 128-line television images of Secretary of Commerce Herbert Hoover from Washington to New York. In 1928

19321-486: Was under Kearny Works. The 1960s and 1970s had various new facilities built and occupied by Western Electric to produce new technologies such as electronic switching equipment (Dallas and North Illinois), fiber optic cable networks (Atlanta), power systems (Phoenix), business equipment (Denver), and telephone equipment (Shreveport). In 1970, Western Electric purchased land in Bishop Ranch, San Ramon, California for

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