Good ideas are hard to predict, both before and after they are introduced as prototypes. The push-button (touch-tone) telephone was conceptually launched to the consumer market at the 1962 Seattle World's Fair, 21 years after the device was invented by Bell Telephone labs. Another 20 years after the Seattle exposition, touch-tone phones finally penetrated 50 percent of American homes. A general lack of tech frenzy, and monopoly pricing control, slowed adoption. But it's also true that the new phones didn't solve a fundamental problem. They sped up dialing, which solved a non-essential but important user
