Vonage Holdings is in the crosshairs of a third major telecommunications company: AT&T last week filed a lawsuit in federal court alleging the Internet phone company infringes on one of the telco's patents.
The suit, which Vonage disclosed Friday, seeks an injunction barring Vonage from using the patent and unspecified monetary damages. AT&T filed the lawsuit Oct. 17 in the U.S. District Court for the Western District of Wisconsin.
Earlier this month Vonage agreed to a patent-licensing deal with Sprint Nextel worth $80 million after Sprint won a judgment that Vonage had infringed six patents.
In a separate suit, brought by Verizon Communications, a federal appeals court last month denied Vonage’s appeal of a lower-court judge’s ruling that it infringed two of Verizon's voice-over-Internet-Protocol patents.
Meanwhile, Vonage last week settled a fourth legal dispute, with Klausner Technologies, a privately held company that owns patents on voicemail technology, for an undisclosed amount.
AT&T's lawsuit alleged that Vonage infringes on U.S. Patent No. 6,487,200, titled "Packet telephone system." Granted to AT&T in November 2002, the patent describes a telephone system that uses a packet network to provide "virtual circuits" and compresses voice calls into data form in short packets.
Vonage said in disclosing the lawsuit in a regulatory filing that it has been "in discussions [with AT&T] to resolve this matter for some time."