The patent, held by a small company called C2 Communications Technologies, is one of 10 that the Electronic Frontier Foundation (EFF) has been trying to strike down for several years through its . On Friday, the patent office granted the EFF's request for a re-examination, the EFF said. The digital civil-liberties organization argued that another applicant had submitted basically some of the same technology to the patent office before C2 did.

Patent No. , "Method and apparatus for implementing a computer network/Internet telephone system," is credited to David L. Turock as inventor and is owned by C2, previously called Acceris Communications Technologies. The patent was applied for in 1995. The company, incorporated in Florida, owns about half a dozen patents and doesn't make any products, according to Stephen Weintraub, executive vice president, secretary and chief financial officer at C2. It is a subsidiary of Counsel Corp., an investment company based in Toronto.

In 2006, C2 sued all the major U.S. carriers, including AT&T, Verizon and Qwest, alleging they were infringing the patent. All the carriers settled out of court with one-time payments, according to Weintraub. C2 believes many more companies are violating the patent, as well as another VoIP-related patent owned by C2. Its patents cover most of the technology used in VoIP, though not all VoIP products may infringe them, he said.

With its Patent Busting Project, EFF is targeting patents that it claims are invalid and hurt ordinary people by threatening innovation. In this case, the patent affects a technology that has made voice calls more affordable and that depends partly on independent inventors for new advances, said EFF Legal Director Cindy Cohn.

"VoIP is one of these kinds of technologies that really frees people," Cohn said. EFF is worried that fear of lawsuits by C2 could inhibit developers from making new VoIP products available. Meanwhile, its patent is one that never should have been granted, Cohn said.