Additionally, by 1942, the company had designed a sophisticated audio system for the University of Minnesota, and the resulting jacks, plugs, patch cords and jackfields became the cornerstones for ADC's later entry into telecommunications.

In 1949, ADC sold its audiometer product line and Ralph Allison left the company to form a new business in California.

With Walter Lehnert remaining as president of the company, ADC diversified and focused its efforts in the area of transformers and filters for power lines, military electronics, telephone jacks and plugs.

Perhaps the most significant product innovation during this period was the bantam jack, a miniaturized component that eventually became the standard for telephone circuit access and patching.

Building on its growing sales of jacks and plugs in the early 1970s, ADC introduced prewired, connectorized jackfields, wired assemblies and test equipment for telephone operating companies.

By establishing the seven Regional Bell Operating Company (RBOC) carriers as independent entities, the U.S. market for telecommunications expanded by 90 percent.

However, their ability to find synergies between these companies proved limited and eventually ADC was forced to move away from a hardware-only strategy, broadening out into software.

This effort resulted in limited success as well, and happening about the same time as the dot-com bubble burst, caused ADC stock to plummet.