It turns out BTI Systems closed a $27 million round of funding in December.

The funding wasn't announced because it includes one investor that didn't want its involvement publicized, says Sally Bament, BTI's senior vice president of global marketing.

BTI has now raised $60 million since recapitalizing in 2010. Bain Capital Ventures was the lead investor in a $23 million round in 2011 and led a $10 million round in 2013.

As part of its second lease on life, BTI plowed lots of money into R&D in 2013, pushing the company into the red. That was an intentional trade-off, Bament says (BTI had been profitable), and the company expects to flip back to positive territory this year, in terms of earnings before interest, depreciation, taxes, and amortization (EBIDTA).

BTI hired a CFO in August and took the occasion to point out its growth trajectory. Revenues for the past five years have shown a 33 percent compound annual growth rate, Bament says.

After years of targeting telcos' metro networks, BTI shifted focus in 2013 to sell its packet-optical equipment to interconnect the data centers of hosting companies and the Web 2.0 crowd. Two named customers are Equinix and VKontakte (VK), the eastern European social network.

Meanwhile, BTI has continued selling to some of its telco customers, so the latest funding will go toward beefing up the sales force across Europe, North America, and BTI's biggest growth region of late, Asia/Pacific, Bament says.

BTI is considered a possibility to go public, especially since the company hired a new CFO last year. The latest funding would presumably push any such plans further into the future, however.