Chicago-based private equity firm Adams Street Partners has led an $8.6 million equity funding round for Five9 Inc., a Pleasanton, Calif.-based maker of cloud-computing software for call centers.

Existing investors Hummer Winblad Venture Capital and Partech International, both of San Francisco, also participated in the round.

The new capital, which brings total funding for Five9 to more than $37 million, will be used to accelerate the company’s growth.

Cloud computing is an increasingly popular technology that enables computer users to access data and software over the Internet.

Five9 said it processes more than 1 billion telephone calls a year for call centers agents. Last year, it was named to Inc.’s magazine’s list of the nation’s fastest-growing private companies.

“Five9 has solved a particularly difficult problem – handling extremely high volumes of real-time telephone conversations in the cloud,” David Welsh, a partner in Adams’ Menlo Park office, said in a statement. “The company has demonstrated tremendous technical capability combined with prudent financial management that has produced sustained profitability through periods of high revenue growth and increasing market share.”

byerak@tribune.com