The lawsuit, filed in a federal court in the Eastern District of Texas, asserts that sales of that iPhone, Visual Voicemail and other visual voice messaging services implemented by AT&T infringe Klausners U.S. Patents 5,572,576 and 5,283,818.
Klausner is seeking damages and future royalties estimated at $360 million.
Owned by a group of private investors, the firm has successfully defended and then licensed the same patents to other industry heavyweights that provide visual voicemail services, including Time Warners AOL for its AOL Voicemail services and Vonage Holdings for its Vonage Voicemail Plus services.
In the latest suit, Klausner specifically alleges that the iPhone violates its intellectual property rights by allowing users to selectively retrieve voice messages via the iPhones inbox display.
"We have litigated this patent successfully on two prior occasions," said Greg Dovel of Dovel & Luner, counsel for Klausner. "With the signing of each new licensee, we continue to receive further confirmation of the strength of our visual voicemail patents."
Separately on Monday, Klausner also filed similar claims against Comcast Corporation, Cablevision Systems Corp. and eBay Inc.s Skype with damages and future royalties estimated at $300 million.
In that case, Klausners alleges that Cablevisions Optimum Voicemail, Comcasts Digital Voice Voicemail and eBays Skype Voicemail each violate intellectual property rights by allowing users to selectively retrieve and listen to voice messages via message inbox displays.