Microsoft lost a lawsuit yesterday in which it alleged that Alcatel-Lucent had violated software patents used in business telephone networks.

The US International Trade Commission (ITC) said on Tuesday that the French-American networking group Alcatel-Lucent was not guilty of infringing four patents for software used in a message and videoconferencing system.

Administrative law judge Paul Luckern had initially ruled that Alcatel-Lucent infringed one of the four patents it pinpointed in Microsoft’s lawsuit. But the commission yesterday overturned that ruling, much to the chagrin of Redmond.

"We are disappointed that the International Trade Commission reversed Judge Luckern's ruling that Alcatel-Lucent infringed Microsoft's '439 patent. We look forward to receiving the detailed ruling so we can understand the Commission's reasoning," said Microsoft in a statement.

The latest ruling follows Microsoft’s separate legal spat with Alcatel-Lucent in August last year when it successfully overturned a $1.5bn ruling made against it for patent infringement. In January 2007 a jury ruled that Microsoft had infringed two patents owned by Alcatel-Lucent relating to MP3 standards and made the record award.

Alcatel-Lucent was not immediately available for comment at time of writing. ®

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