Bell Laboratories Record Vol 54 Bell's great invention: life begins at 50

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T WAS the jazz-bewitched 1920s. Depression clouds still hung over That decision paid off. The 500- Movies became talkies in 1926 1937 when the third generation of type set appeared in 1949. With with the first full-length motion pic- desk phones-the 300-type tele- years of research and development, ture using equipment developed by phone set-was born. A much im- plus human-factors engineering be- . The same year the tele- proved design, the set's bell and as- hind it, the fourth-generation 500 phone, a necessity now in millions sociated equipment were in the base set added even more naturalness of homes and businesses, celebrated instead of in a separate wall box. and intelligibility to speech. Styling its 50th birthday. The 300 set was the first phone to was modern, and the adjustable The pedestal-or candlestick- have an anti-sidetone network that ringer was more effective. The user desk set was the instrument of the minimized the sound of your own could set it to ring loud or soft, and era, although many of the earlier voice in the receiver as you spoke. it was lower pitched. The improved wall phones were still in service. N a- A new transmitter and a new re- transmission and ringer allowed the tionwide calling using long-distance ceiver helped improve fidelity, and 500 set to operate on circuits with operators was commonplace. Some the set was less susceptible to line higher resistance. Thus, sets could phones had dials that could be used noise. be used at greater distances from for local calls. A year after the 300 set's intro- switching offices, or at short dis- But the world was moving faster, duction, six buttons were added to tances using smaller diameter wires, and customer demand for more and it-hold, plus five lines-making saving copper. better communications facilities the phone the 's first manufactured the 500 set so effi- was swelling. self-contained key set. ciently that its price to Operating The newly formed Bell Labs had It was a welcome change for busi- Telephone Companies was well be- the job. Engineers and scientists nessmen. At the time they had a low that of any other telephone in set about improving the telephone separate phone for every line and the world. set's voice transmission quality, im- the result was often a desk cluttered Available in many colors after proving its reliability, increasing with phones. 1954, the 500 set remains the most the number of services a phone World War II turned a good part widely used telephone in the U. S. could provide, reducing cost, and of Bell Labs effort to the nation's Exploiting newly developed mate- designing a variety of instrument defense. But right after V.J. Day, rials and processes, Bell Labs and styles to satisfy every taste. development resumed on new sta- Western Electric have made more Just before the crash of '29, the tion equipment for home and office. than 2500 changes to the 500 set in second generation of desk phones One of the first tasks was a new its lifetime, not just for the sake made its debut for Bell System cus- station set with higher receiving of appearance, but to make it work tomers. It was a "new look" set- volume, a better dial, lighter hand- better and to keep its cost down. a milestone in telephone evolution. set, and an improved ringer with a Nevertheless, with the exception of A streamlined version of European volume control. Originally these the TOUCH-TONE® dial, all tele- phones, the set was popularly known were intended as improvements in phones manufactured today contain as the "French phone." It came in the 300 set, but the Bell System de- components that have essentially bronze, gold, silver, gray, ivory, and cided to go for a completely new the same characteristics as those of "basic black." design. the 500 set.

:rom past to future: Fifty years ago, only a battery of phones 115 give a customer multiline service. Then came the six-button y telephone with five lines plus hold. Today do en more-witness the Transaction telephone for the "cashlessBell Laboratories Record Vol 54 society's" banking and credit services and, of course, regular lephone service. ful addition to the product line. First offered in six colors, the set required redesign of the 500 set's ringer, speech network, and dial, and the addition of a lead weight in the base. Nevertheless, the Princess phone's performance was the same as the 500 set's. .Two-line Princess phones with Touch-Tone dials and new colors made the scene in '63. During this period the business customer's needs were also getting attention. Although six-button key sets provided five lines in a single telephone, there was a growing need for additional lines and improved service among businesses that were Group calls have been made easy with the Bell System's 4A speakerphone. too small to warrant having their own "switchboard." To fill the vac- uum, the Bell System introduced Realizing that many telephone speakerphone. The introduction of the CALL DIRECTOR® telephone in users would like to keep their hands integrated circuits resulted in the 1959. Employing the basic 500-set free for note-taking or to look up elimination of a separate control speech circuit and handset, it could reference material during conver- box. The overall transmission was serve as a regular office phone and sations, Bell System engineers de- improved, providing more natural handle several incoming, outgoing, veloped the speakerphone. The first group discussions over the tele- and interoffice calls at once. model appeared in 1954 (but the phone; however the "barrel effect" This single instrument serves as quality of the sound produced what still remains as a problem in the use the receptionist's "extension" of some users described as the "barrel of speakerphones. each phone in a customer's office. effect"). An automatic voice-switch- After years of using telephones Present models handle up to 29lines ing circuit, added to the 1959 speak- that, except for different colors, and come with a variety of options erphone, improved performance by looked alike, some Bell System cus- for line selection, signaling, and eliminating "singing" from acoustic tomers were ready for a change- built-in speakerphone. feedback. Further research pro- a new and different phone, smaller, In the whirlwind world of the late duced a new, transistorized voice- more decorative. Sensing the mood, '50s, jets started cutting travel time switching circuit that included, the Bell System introduced the in half. The stage was set for ways among other improvements, a noise- PRINCESS® phone. (A name once con- that would save telephone customers operated, gain-adjusting device sidered for it was the "bedroom dialing time too. Telephones were which discriminated between speech set.") Advertisements proclaimed being designed that would automa- and noise signals at the microphone. "It's little, it's lovely, it lights," and tically dial often-called numbers. It The circuit was used in the 3-Type the mold of traditional telephone happened in 1961 when the Bell speakerphone which was intro- design was broken when the phone System introduced the automatic duced in 1960. bowed in 1959. Sporting a new look card dialer, which used perforated Speakerphones, of course, were and a dial that lit when the handset plastic cards to store numbers. commonly used for calls between was lifted, the phone was a success- Automatic dialer design expanded groups of persons. And persons who in 1965 with the CALL-A-MATIC® liked to dominate the conversation set, which used tape cartridges to soon learned to sit right in front store 250 or 500 numbers. of the microphone. Why? Because Today's family of TOUCH-A- sometimes speech quality suffered if MATIC® telephones contain inte- someone sat to the side of the mi- grated circuits that perform mem- crophone, or walked about while ory, logic, and dialing functions. talking. To pick up voices well The first Touch-a-matic telephone, around a table or room, an omni- introduced in 1974, is slightly larger directional microphone was incor- than a standard desk phone and porated in 1973's two-piece 4A stores 31 numbers permanently-

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Bell Laboratories Record Vol 54 at least until changed by the user. and operating force. Then, in 1963, Market studies revealed such a the Touch-Tone telephone was born. number would be adequate for the Touch-Tone service cuts manual majority of customers. To dial a dialing time in half and quickly re- frequently used number, just press leases switching machines to handle a button. But what about numbers other calls. Touch-Tone phones al- you don't dial that often? Bell Labs low people to "talk" with comput- engineers added another button ers-to bank and to shop by phone, that will automatically re-call the to verify checking-account balances, last manually dialed number if the and to make it possible for stores to line were busy or if the party didn't "dial up" the status of a customer's answer. In late 1975 a version of charge card. By the early 1980s, the phone was offered without a Touch-Tone service will be avail- handset as an adjunct dialer for ex- able to about 85 percent of Bell Sys- tem customers. Imagine a complete phone in the Dreyfuss culminated in 1965 with palm of your hand-one with a dial a phone that looked like a fine piece right in the handset for comfortable of sculpture. The Bell System's calling from a chair, bed, or while "beauty queen," it was called the working in the kitchen. Not requir- TRIMLINE phone and was chosen ing a long reach for the dial-in-base, by the Museum of Modern Art in the phone could be kept in places New York City for its Design Col- that would be awkward for stand- lection. Balancing technological and ard phones. Such a dial-in-handset aesthetic considerations, the Trim- phone had been around since 1941, line phone was the first to have the but it was a lineman's handset and dial and transmission circuitry in isting phones. The single-line not attractive enough for home or the handset with the transmitter Touch-a-matic 16 telephone for res- business use. and receiver. idential and small-business cus- So Bell Labs engineers sat down Another Trimline telephone tomers came out the same year. at the drawing board. The first trial "first" was the concept of modular- Of course, the venerable tele- design of a dial-in-handset phone ity. That is, the phone's handset, phone dial was meeting competition base, and connecting cords are fitted in other quarters, too. The inven- with plugs and jacks. The phone tion of the transistor in 1947 company orders separate parts that spurred development of other elec- the installer assembles on the cus- tronic devices, and soon a whole new tomer's premises. Modularity re- array of miniature components be- duces the inventory of phones on came available. Putting them all to- an installer's truck to handsets, desk gether, engineers designed a com- bases, wall plates and cords in stand- pact, solid-state multi-frequency ard colors. When moving, custom- pushbutton tone oscillator. At the ers can unplug the phones, pack same time human-factors engineers them, then plug them into connect- made tests on volunteer "dialers" ing blocks in their new homes. In- to determine the best button ar- corporating a specially designed rangement, size, spacing, travel, for subscribers was called the Demi- ringer, network, (or tasse; it was a standard handset Touch-Tone pad), and receiver, the with a dial over the transmitter. In Trimline phone now outranks the 1959·, Bell Labs came up with an- 500 set in production rate. other design with a standard dial With an eye on easier, low-cost between the transmitter and re- maintenance, the Bell System also in ceiver. Still too bulky to be prac- 1965 introduced the single-slot coin tical, the midriff bulge earned it the phone. Quite different both out- nickname "Schmoo" because of a wardly and internally from its resemblance to AI Capp's genial three-slot predecessor, the phone is cartoon character. Further design more resistant to vandalism, has a effort by industrial designer Henry larger cash box, and provides im-

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Bell Laboratories Record Vol 54 Classroom lectures reach distant groups with the Portable Conference Telephone.

proved coin-sensing to detect slugs. Engineers were encouraged by The variety of phone styles avail- The single-slot coin entrance elim- the economics of modularity, intro- able to Bell System customers grew inates fumbling to get the coin in duced by Trimline phones, so they larger in 1974 when DESIGN LINE the right slot, making for faster extended it to all phones in 1972. telephones were announced-there deposits. Modular phones have been the key are colors and styles for every room, Since the introduction of speaker- to success of PhoneCenters where period, mood, decor, or whatever. phones, the Bell System recognized customers sign up for service, pick Five models were offered first; now the need for a similar but larger in- up their phones, bring them home, there are 11. The telephone com- strument for classrooms, conference then plug them into pre-installed pany's investment is minimized be- rooms, and auditoriums. The result modular connecting blocks. Starting cause the phones can be shipped di- was the Conference Telephone Set early this year, all single-line desk rectly from Western Electric to the in the mid '60s. Packaged in a small and wall phones installed will be customer. They are also the first suitcase, it could be carried any- modular. sets in which the "shell," or non- where and plugged into a telephone working part of the telephone, is jack, permitting a classroom lec- sold by the Bell System. turer to speak to remote classes. In response to requests from Bell One university created a network System Operating Companies, Bell of 50 sets using the 50A Portable Labs designed a business telephone Conference Telephone brought out set that enables merchants and in 1970. In 1975, the Bell System in- banks to check credit-card transac- troduced the 50A1 Portable Con- tions in seconds. Developed with ference Telephone. guidance from A T&T's marketing A large step in communications department and introduced in 1974. was taken in 1970 when PICTURE- the Transaction telephone is twc PHONE service was introduced on phones in one. The first is for nor· a limited basis, enabling users to mal calling, the other for informa. see each other and to display graphic tion exchange with a computer, for material. The Picturephone set was check verification and credit author· a technological challenge, involving ization by stores and banks. the packaging of a TV camera and The phone will also allow depos receiver. It is still being evaluated itors to verify their checking-ac to find its place in business and count balances without a cashier the home. In one version this communicatim

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Bell Laboratories Record Vol 54 and a privacy key to prevent the room from being monitored SPECIAL PHONES FOR SPECIAL NEEDS by the nurse. Patients who can't reach the phone use a nurse's call button, plugged into the phone's base. Before we close out the century of telephone develop- The 18781ineman's handset, which the "French phone's" ment, a few words about not-to-be-forgotten special-pur- handset was modeled after, was updated in 1941 and again pose phones for those unusual needs ... in 1968. Police! Fire! An emergency reporting telephone for street For hard-of-hearing persons, there are handsets with use appeared in bright red or yellow cast-metal boxes in amplifiers to boost volume. Persons with soft voices can 1955; an improved model came out in '63. Opening the get a handset with an amplifier to boost the transmitter's door and lifting the handset automatically connected you output. with the centralized reporting bureau. The Code-Com set enables deaf and blind-deaf cus- There's a phone for elevators, and another for hospital tomers to communicate by watching a flashing light or patients. The hospital phone has keys that control a touching a vibrating disc. A key lets the persons "talk" by speakerphone (to the nurse's station), a nurse's call key, Morse code. with a computer includes a com- the computer-generated voice an- Unquestionably, today's tele- puter-generated voice answer-back swer-back feature, the phone has phones are a far cry from the first arrangement. an eight-character display that commercial set. The terminals of a The Transaction II telephone will shows information about the trans- vast, complex communications net- become available this year and, like action. All of these communication work providing essentially instan- its predecessor, will "read" mag- capabilities are achieved through taneous communications, telephones netically encoded stripes on the mer- the application of the latest solid- from the beginning have met a chant's dialing card and the cus- state, large-scale integration into great social need, essential to the tomer's credit card. In addition to the telephone. nation's growth and prosperity. D

ALONG WITH THE TELEPHONE, OTHER BIG INNOVATIONS ... While the development of telephone sets was progressing, part of the signal coming from the amplifier for comparison Bell Labs was making important advances in almost every with the signal coming into it. It made possible multi- other area of telephone technology. Here are some of those channel cable systems. innovations: Direct Distance Dialing. Bell System customers began Transistor and Solid-State Electronics. Modern solid-state dialing long distance calls without operator assistance in electronics-commonplace today in the design of essen- 1951, a change requiring the development of a nationwide tially all telecommunications equipment, computers, tele- uniform numbering plan and an automatic accounting sys- vision sets, pocket calculators, pacemakers, and so on- tem as well as new signaling techniques and switching was realized with the invention of ,the transistor by three equipment. Today, direct distance dialing is virtually uni- Nobel Prize-winning scientists at Bell Labs in 1947. versal and is being extended to international service. Logic Control Systems. The early use of digital logic to Encoding of Signals. The formulation of an information store and interpret dialed information for telephone switch- theory at Bell Laboratories in the mid-1940s provided a ing led to the design and operation at Bell Labs of the first complete mathematical theory of communications-and electrical digital computer in 1937-and to a variety of led to better understanding of the design of digital trans- electronic switching systems. The systems store instruc- mission systems, the first of which was introduced in 1962. tions for new customer features and services in computer- The systems carry calls as encoded pulses rather than like memories, easily changed without rewiring or replac- continuous signals. ing equipment. Quality Assurance. Scientific methods of statistical quality Improvements in Cable Transmission. Since the invention control, now used by industry throughout the world, were of the coaxial cable system at Bell Laboratories in 1929, developed half a century ago in the Bell System. improvements in this transmission medium have con- Vacuum Tube Amplifier. Research at Western Electric and tinued to the cost of long-distance Today, a General Electric Company created a higher vacuum in pair of conductors can accommodate over the three-element tube, invented by Dr. Lee De Forest, simultaneous about times as many as when making it a useful amplifier. Vacuum tube amplifiers were a system went into commercial service in 1941 . placed at intervals along the first transcontinental tele- Microwave Radio Transmission. After years of research, phone line, boosting voice signals before they weakened the began using microwave radio commer- and faded away. in 1948 to transmit and television Network Theory and Filters. Theoretical investigations of With microwave radio, long-distance transmission was no electrical networks led in 1917 to the invention of the elec- dependent on and each radio tric wave filter, which made it possible to carry many con- carry many 1962, with the versations on a line at the same time. A World War II of the of microwave trans- shortage of high-grade natural quartz, from which the mission was to communications. filters are made, prompted development of man-made Negative Feedback. were caus- quartz crystals by Bell Labs and Western Electric. The ing noise and distortion in the part of the 1920s, synthetic crystal could control frequencies with the same a technique was discovered at Labs for stability and precision as natural quartz.

Bell Laboratories Record Vol 54