This manufacturer of telecommunications equipment was established in 1975 by Michael Birk and others in Lisle, just west of Chicago. The company started with 20 employees and grossed about $300,000 in sales during its first year. The federally mandated breakup of AT&T in the early 1980s helped Tellabs by increasing the number of potential customers. Annual sales surpassed $100 million in 1985. The strong telecommunications market of the middle to late 1990s provided fertile ground for Tellabs' exponential growth during that decade. The company was headquartered in suburban Naperville by 2000, boasting $4 billion in revenues and 8,000 employees around the world, almost half of those in Chicago. Tellabs followed its industry downward in the early 2000s, dropping two-thirds of its sales and cutting its workforce to about 4,000, one-third of whom worked outside the United States.

This entry is part of the Encyclopedia's Dictionary of Leading Chicago Businesses (1820-2000) that was prepared by Mark R. Wilson, with additional contributions from Stephen R. Porter and Janice L. Reiff.