Update: Vonage sued for voicemail patent infringement

The technology used by Vonage Holdings  to deliver voicemail service to its 1.6 million VOIP (voice over Internet Protocol) telephony customers infringes another company's patent, according to a lawsuit filed Monday.

Klausner Technologies  has asked a federal court in the eastern district of Texas to fine Vonage $180 million in damages and royalties for the patent infringement.

Klausner, a privately owned company that controls 25 patents for VOIP voicemail technology, already collects licensing fees from Time Warner Inc. for using this technology in its AOL Voicemail and VOIP voicemail services.

The company asked Vonage, of Holmdel, New Jersey, to sign a similar agreement in January, but the only response has been a request for more time, Klausner claims.

Vonage did not reply to requests to comment for this story.

This is the second patent infringement suit to hit Vonage in recent weeks. In June, telecommunications giant Verizon Communications Inc. leveled a patent infringement lawsuit claiming that Vonage relies on seven of Verizon's patented technologies to make its VOIP system work.

Vonage, a relatively small company that went public in May, is fighting back with its own lawsuit. Also Monday, Vonage announced it had acquired three VOIP patents from Digital Packet Licensing Inc.

The new patents are unrelated to voicemail; they concern the compression of packetized digital signals. But they allow Vonage to control license agreements with competitors like Motorola Inc., Time Warner and Qwest Communications International Inc., and to continue a federal patent infringement lawsuit against two other competitors, Sprint Communications LP and Verizon.

This story has been corrected.