Vonage sued for patent infringement--again

Patent-holding company Klausner Technologies said Monday it filed suit against Vonage in federal court in the eastern district of Texas. Klausner claims that Vonage, which sells Internet voice calling service, is infringing on patents being used as part of its voice mail service. Klausner is seeking damages and royalties worth about $180 million.

Vonage is already being sued by two large phone companies for supposedly infringing on patents. Last year, a subsidiary of Sprint-Nextel filed suit against Vonage. Then, in June, Verizon Communications filed suit against the company, claiming it had infringed on seven patents that describe technology for completing phone calls between voice over Internet Protocol (VoIP) users and people using phones on the traditional public switched network.

Separately, Vonage said Monday that it has bought three patents from Digital Packet Licensing for an undisclosed amount. Vonage said the patents will help it in its fight against the Sprint and Verizon litigation. Companies such as Motorola, Time Warner and Qwest Communications are already licensing technology from Digital Packet on these VoIP patents. As a result of acquiring the VoIP patents, Vonage also assumes ownership and control over these agreements.

"We're committed to developing, acquiring and protecting the root technologies that are at the heart of our business," Michael Tribolet, president of Vonage America, said in a statement. "The acquisition of these patents is part of Vonage's strategic plan to further develop our core technology and build on our innovative, affordable and feature-rich phone service. Vonage's strategic plan also includes a concerted effort to grow, create and acquire other significant intellectual property portfolios."

The latest lawsuit has comes as Vonage tries to recover from a disappointing stock market debut. The company lost nearly 30 percent of its value in the first week of trading. The Internet telephony provider has also been gearing up to defend itself against several investor lawsuits. Shareholders allege that the company misled them and created artificial demand for the stock.

Klausner, a privately held company that controls several patents for voice over IP technology, settled a lawsuit earlier this year with Time Warner for using its technology in AOL voice mail. Under the settlement, Klausner granted a license to AOL to use the patent. Financial terms were not disclosed.