Model 500 telephone

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. Millions of model 500-series phones were produced and were present in most homes in North America. Many are still in use today because of their durability and ample availability. Its 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 * and # keys, and is still produced by several manufacturers.

The Western Electric 500-type telephone replaced the 300-type which had been produced since 1936. Like its predecessor, 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 and lead 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 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, systematic replacement of 25 million 300-type telephones commenced because of the much improved electrical and acoustic efficiency of the new model. 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.

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