Alcatel-Lucent appeared before a federal appeals court asking that a $1.53 billion jury verdict for it against Microsoft be reinstated, a Dow Jones report said.
The case, in which Alcatel-Lucent says Microsoft's Windows Media player infringed on two of its patents, has the highest profile of several patent cases pending between the two companies, the Dow Jones report added.
Alcatel-Lucent Spokeswoman Mary Ward was quoted by the Dow Jones report saying the company plans to defend its patents aggressively.
'The reason we're pursuing this particularly vigilantly is this is our intellectual property. It's really a vital asset, and we're going to defend it.'
At trial last year, Alcatel-Lucent argued that Microsoft's audio software violated its patents relating to MP3, the most popular file format used to store digital audio.
Last August, a district court judge said Microsoft didn't have to pay the $1.53 billion jury award because it wasn't in violation of one patent and had licensing rights to the other, the Dow Jones report said.
On the second point, the judge cited a joint ownership agreement of the MP3 patent held by Germany's Fraunhofer Institute and AT&T.
The Dow Jones report further said during oral arguments Monday before the US Court of Appeals for the Federal Circuit, Microsoft's attorney John Gartman defended Microsoft's licensing agreement with Fraunhofer, saying that license covers the patents asserted by Alcatel-Lucent.
Gartman told the three-judge panel that the joint ownership rights held by AT&T and Fraunhofer extend to any license or intellectual property that stems from their collaboration.
Alcatel-Lucent initially sued computer makers Gateway and Dell over a series of patents in 2003, and Microsoft subsequently stepped in on their behalf. Alcatel-Lucent claimed computers made by Gateway and Dell using Microsoft products infringed on its patents.
A judge later divided the case into several parts based on the types of patents involved.