The deal is the first outside investment in the 18-year-old company's history. While some of the funds will go to cash out founders' equity, the majority will be used to expand technology capabilities and scale up business functions to accommodate growth that has tripled REVShare's media billings since 2003.

REVShare founder and CEO Joseph Gray attributed much of the increased interest in cost-per-action, or CPA, which allows advertisers to pay for ad time on a schedule tied to consumer response, to growth in Web advertising, and he said investor interest has increased over the same period.

"The business has become much more of a growth business as direct response became very mainstream, and that has been a fundamental shift starting about 10 years ago," Gray said. "There has been a lot of change in the television industry, but there also has been a lot more acceptance of response advertising by brand advertisers, and that APA traction has been brought about by online advertising."

REVShare operates a proprietary bidding system that allows advertisers to specify a price they are willing to pay for each consumer response to a toll-free number or Web site, and air time is sold based on return on investment. The system allows television stations to sell advertising on this basis in a competitive pricing model, but without broadly disclosing pricing.

Gray said that differentiates it from Web advertising systems that have a more open auction system, and he said that has allowed the company to succeed, while efforts by online advertising leaders including Google Inc. to translate their business models to TV have met resistance.

"Television stations don't want to commoditize their ad space, and having been in business for 20 years, we are very cognizant of the political issues," Gray said. "We have relationships with 1,500 stations, and they all utilize the system in a way to increase revenues, but in a way that is safe to their overall business model."

Josh Ofstein, a principal with Carlyle Group in San Francisco, said the firm was introduced to the deal by HIG and was attracted to REVShare's established role in the industry as the only significant company offering cost-per-action advertising on television.

"This is a very large market opportunity and a disruptive business model, and the network they have built is a very high barrier for entry," Ofstein said. "Carlyle has a large footprint in media, and we think we can be helpful both in media and with large advertisers."

With the new investment, Ofstein will join REVShare's board of directors, along with John Kim of the Miami office of HIG.

Gray said the company will invest much of the new capital in additional technology, and the company is working closely with cable systems as they roll out new interactive features, but he said it will also invest in scaling up administrative and sales and marketing functions as the company grows. He said REVShare has no short-term plans to raise additional capital.

REVShare worked with Patrick Murphy and Timothy O'Brien of Stradling Yocca Carlson & Rauth in closing the round. Mark Baudler and James Behan of Wilson Sonsini Goodrich & Rosati PC in Palo Alto, Calif., represented investors.