For the second time in less than a week, Apple has been sued for patent infringement in the Eastern District of Texas, long seen as a plaintiff-friendly venue for patent litigation.

New York-based Klausner Technologies filed the patent-infringement lawsuit Wednesday against both Apple and AT&T Mobility, claiming that the two companies have violated its 1994 patent, "Telephone answering device linking displayed data with recorded audio message."

Last week, Apple was sued in the Eastern District of Texas for allegedly infringing on the patents of Mirror Worlds, a company that sold desktop search and organization software in the early 1990s.

This week's lawsuit is a revision of one filed on Dec. 3 by Klausner Technologies that cited an additional patent (U.S. Patent No. 5,572,576) and named more defendants: Apple, AT&T, AT&T Mobility, Comcast, CSC Holdings, eBay, GotVoice, and SimulScribe.

Klausner Technologies was founded by Judah Klausner, who claims to have invented the PDA and electronic organizer. A Dec. 3 press release announcing his company's initial lawsuit claimed that Apple licensed technology for its Newton PDA from Klausner, under U.S. Patent No. 4,117,542.

"The iPhone violates Klausner's intellectual property rights by allowing users to selectively retrieve voice messages via the iPhone's inbox display," the December release stated. It also said that Klausner's patent has been successfully litigated twice before.

The Klausner Technologies patent describes a "telephone answering device (TAD) which includes a means of intelligently organizing voice messages, associated entered codes such as personal IDs and home telephone numbers, and information stored in the memory of the TAD."

The patent's arguable innovation is the ability to access voice messages nonsequentially. By preassigning identifier codes to callers, users can access messages from a list. "This enables the user to access messages in a selective manner based on the identity of the caller," the patent explains. "The need to listen to the actual voice messages to determine the caller's identity and the need to listen to the messages sequentially or chronologically is obviated, saving both time and effort."

On its Web site, Apple highlights similar functionality for its iPhone: "An industry first, Visual Voicemail allows you to go directly to any of your messages without listening to the prior messages. So you can quickly select the messages that are most important to you."

Klausner Technologies holds several telephone audio patents. Vonage last year settled a patent suit brought by Klausner for an undisclosed amount.

Michael C. Smith, a partner in the law firm of Siebman, Reynolds, Burg, Phillips & Smith, blogs about his patent litigation practice in the Eastern District of Texas. Last week, he cited an article in American Lawyer than noted defendants becoming increasingly successful in patent cases. He said that through late 2006 and 2007, defendants posted a 2-to-1 win rate over plaintiffs.

In his Patently-O blog, Dennis Crouch, associate professor at the University of Missouri School of Law, cites the work of James Bessen and Michael J. Meurer, who present evidence in their book Patent Failure that the current patent system does more harm than good.

Bessen and Meurer claim that "in industries other than chemicals and pharmaceuticals, defense against American patent lawsuits amounts to 13% of R&D spending by defendant firms (19% in 1999). In contrast, our studies of patent value indicate that worldwide patent value amounts to only 6% of R&D spending by these same firms. The result -- patents impose a tax of at least 7% on R&D investments outside of the chemical and pharmaceutical industries."

An Apple spokesperson wasn't immediately available to comment. Apple typically does not comment on pending litigation.