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Model 500 telephone

Model 500 telephone is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Model 500 telephone rather than just read about it. In short: The Western Electric model 500 telephone series was the standard domestic desk telephone set issued by the Bell System in North America from 1950 through the 1984 Bell System divestiture. The successor to the model 302 telephone, the model 500's modular construction compared to previous types simplified manufacture and repair and facilitated a large number of variants with added features.

Model 500 telephone — main illustration
Model 500 telephone — illustration

Key takeaways

  • Model 500 telephone belongs to science; place it in that map before memorising details.
  • Learn the definition first, then one example that makes the definition concrete.
  • Connect Model 500 telephone to a quantity you can measure, compute or draw — that is where exam questions come from.
  • Reproduce the core statement of Model 500 telephone from memory before moving on to harder problems.

Reference excerpt

The Western Electric model 500 telephone series was the standard domestic desk telephone set issued by the Bell System in North America from 1950 through the 1984 Bell System divestiture. The successor to the model 302 telephone, the model 500's modular construction compared to previous types simplified manufacture and repair and facilitated a large number of variants with added features. Touch-tone service was introduced to residential customers in 1963 with the model 1500 telephone, which had a push-button pad for the ten digits. The model 2500 telephone, introduced in 1968, added the * (star) and # (square, pound) keys. The model 500 telephone series and its derivatives were very popular and common among North American businesses and households throughout the latter half of the 20th century. The development of new simpler telephone set designs, the advent of mobile phones, and the decline of traditional landlines into the 21st century led to the decline of the model 500 series and its derivatives, and most sets still in use are primarily kept by seniors and phone enthusiasts for familiarity, collecting, and nostalgia. However, the model 2500 is still produced by several manufacturers as of the early 2020s, with modernized components to ensure compatibility with modern Bluetooth and voice over IP telephony systems.

History The Western Electric 500-type telephone replaced the 300-type, which had been produced since 1936. The model 500 line was designed by the firm of industrial designer Henry Dreyfuss, the product of several years of research and testing in collaboration with Bell Laboratories and Western Electric. Development started in 1946 with early sketches by Bell engineer and Dreyfuss associate Robert Hose, leading to pre-production units in 1948 and field trials with 4000 telephone sets in 1949. AT&T announced the new telephone publicly in 1949 and communicated the first availability of approximately 23,000 sets in the second quarter of 1950 to the Bell System operating companies on May 1, 1950. Third and fourth-quarter production was estimated at 49,000 and 93,000, respectively. Including 20,000 units of a special purpose set (501B), approximately 183,000 units were produced by the end of the first production year. In the following years, the systematic replacement of 25 million 300-type telephones commenced because of the new model's much improved electrical and acoustic efficiency. This efficiency permitted the new model to be used on long rural loops, which previously required special sets with local batteries to power the transmitter, not just on urban short loops because it contained a self-adjusting gain control. This also permitted the use of thinner loop wires and thus delivered cost savings in the build-out of the network. A 1953 Western Electric ad noted that the “500” phone “has already been introduced on a limited scale and will be put in use as opportunity permits, in places where it can serve best.” The replacement of 300-series telephones with 500-series sets created large stockpiles of 300-type components that had not reached their intended service life. The accelerating demand for new telephone service in the 1950s created pressure on the manufacturing facilities, which the Bell System alleviated by reusing these older components to refurbish used 302 telephone sets with a new modern housing that had a look-alike appearance to the 500 models, but were electrically identical to the older 302 telephones. This program commenced in 1955, and the converted set was labeled as the model 5302 telephone. It was produced until the mid-1960s in the refurbishing shops of each Bell Operating Company, not on the assembly lines of Western Electric factories. From the 1949 field trials until 1953, only black sets of the 500-type telephone were manufactured. Telephones in color were introduced in several stages from 1954 until 1957, as manufacturing capability was refined and material selection processes were completed. In the 1960s, after the introduction of touch-tone service in November 1963 in various locations of the telephone network, the basic 500-type chassis was retrofitted with a new housing and face plate, and a ten-key push-button keypad. This was designated as the model 1500 telephone, and a twelve-button model 2500 was introduced in 1968. The 1970s brought the conversion to modular connector technology, replacing the hard-wired cords with cords terminated on both ends with 4P4C connectors for the handset cord and 6P4C plugs for the line cord.

Ownership and AT&T divestiture As with most telephones in the United States, the 500-series telephones were owned by the local Bell Operating Company and leased on a monthly basis to customers. Choices for telephone styles and colors were limited. AT&T, the principal owner of the operating companies and Western Electric, strictly enforced policies against buying and using telephone sets by other manufacturers on their network to ensure the technical integrity of their network and avoid competition. Most phones made by Western Electric, starting in about 1968, carried this disclaimer molded into their housing: "BELL SYSTEM PROPERTY--NOT FOR SALE." Telephones were also sometimes labeled with a sticker or ink stamp marking the operating company's name that owned the phone. After consumers started buying telephones from other manufacturers, in the wake of legal developments not favoring AT&T's ban against third-party equipment, AT&T changed its policy for the Design Line telephone series by selling customers the telephone housing but retaining ownership of the electrical components, so customers were still required to pay AT&T a monthly leasing fee. In 1983, after the court ordered the Bell System divestiture, AT&T started selling telephone sets outright to the public through its newly created American Bell division. Many customers were offered the option to buy the leased telephones they had in service. AT&T closed its USA consumer telephone manufacturing plants in 1986 and moved production offshore to Singapore, China, and Thailand, and in the 1990s to Mexico; this let them produce telephones at a lower cost.

Design features

… excerpt ends here. Continue reading the full article.

Illustrations

Model 500 telephone: Western Electric model 500 telephone made in the 1950s
Western Electric model 500 telephone made in the 1950s
Model 500 telephone: By 1975, the model 500 design was essentially unchanged, but it used a revised dial, modular cords, and was available in a variety of new colors.
By 1975, the model 500 design was essentially unchanged, but it used a revised dial, modular cords, and was available in a variety of new colors.
Model 500 telephone: Internal components of a model 500 produced in 1951
Internal components of a model 500 produced in 1951
Model 500 telephone: The 425A network component of a model 500 produced in 1951
The 425A network component of a model 500 produced in 1951
Model 500 telephone: A 1959 Western Electric model 554 wall phone, derived from the model 500 desk phone. It uses the same internal components, dial, and handset as a desk phone.
A 1959 Western Electric model 554 wall phone, derived from the model 500 desk phone. It uses the same internal components, dial, and handset as a desk phone.

Worked examples

Example 1 — a first encounter with Model 500 telephone

Start with the simplest possible case. Write down what Model 500 telephone claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Model 500 telephone before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Model 500 telephone ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Model 500 telephone

In research
Model 500 telephone appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry
Engineering practice reuses Model 500 telephone in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom
Model 500 telephone is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1950 introductions, Telephony equipment, Western Electric telephones, so understanding it makes those chapters shorter.
In everyday life
Look for Model 500 telephone outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.
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How to study Model 500 telephone in 20 minutes

  1. Read the reference excerpt below once, without taking notes.
  2. Close the page and write down what Model 500 telephone means in your own words.
  3. Compare your version with the excerpt and mark what you missed.
  4. Work through the three examples above with pen and paper.
  5. Explain Model 500 telephone out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Model 500 telephone in simple terms?

The Western Electric model 500 telephone series was the standard domestic desk telephone set issued by the Bell System in North America from 1950 through the 1984 Bell System divestiture. The successor to the model 302 telephone, the model 500's modular construction compared to previous types simpl…

Why does Model 500 telephone matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Model 500 telephone?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Model 500 telephone.

Tags

  • 1950 introductions
  • Telephony equipment
  • Western Electric telephones

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