High Quality Content by WIKIPEDIA articles! The Western Electric model 500 telephone series was the standard desk-style domestic telephone set issued by the Bell System in North America from late 1949 through the 1984 Bell System divestiture. Millions of model 500-series phones were produced and were present in almost every home in North America. Many are still in use today thanks to their durability and ample availability. Its modular construction made manufacture and repair simple, and facilitated a large number of variants and derivatives with added features. Touch-Tone was introduced to home customers in 1963 with the model 1500 telephone, which had only the 10 number keys. In 1968 the model 2500 telephone was introduced, which added the * and # keys. The model 2500 is still in production today by several manufacturers, over 40 years after it was introduced.