Sundeep Sanghavi's job at Cable & Wireless USA Inc. had been to look for mistakes in the bills the company received from other telecommunications carriers.

Some of the bills came in digital form, including online bills, and were easy to search, but fully half of them arrived on paper. Thousands and thousands of sheets of paper. Over three years at Cable & Wireless, Sanghavi managed to save the company $264 million on the digital bills, but he never found a way to efficiently work through the reams of paper.

"What I'd learned is that if this is a mess across the industry, I could do this," and help telecom companies everywhere save money, Sanghavi said.

In April 2001, in the face of a bad technology market, Sanghavi invested his and his brother's money to start Nexus Innovative Systems Co. to do just that: take the tens of thousands of paper bills a company receives and convert them to digital spreadsheets so that they can be audited just like electronic bills.

Sanghavi's wife, Sonia, an experienced programmer, helped develop the software. Now the Fairfax company has 30 employees and has generated a profit every year, he said. Although Nisco's customers are all telecommunications companies, eventually the company wants to sell its service to large companies that spend millions on their wireless, local, long-distance and Internet-service bills.

Saving money by monitoring bills is an area many software makers have tried in recent years, especially because money has been tight.

"This is a huge, huge area and many companies have been tackling managing costs," said Christa Degnan, research director at Aberdeen Group in Boston. In the Washington area Broadmargin Inc., Teoco Corp., and Vibrant Solutions Inc., all of Fairfax, and Invoice Insight, LLC of Manassas are among dozens of companies that have built businesses doing this kind of work, she said.

Telecommunications firms are good targets for such bill-watching because their bills are often complicated. Local long-distance and wireless carriers pay to use each others' networks, and the rates they pay are always changing, which is why so many mistakes occur. Seven to 12 percent of bills end up in error, Degnan said.

The market could grow, as large companies that spend tens of millions of dollars on telecommunications costs start using similar software to manage their own costs, she said. But even as more businesses spend money on these services, Nisco will have to share the pie with plenty of other players.

Sundeep Sanghavi is founder and CEO of Nexus Innovative Systems Co., a paper-invoice monitoring firm.