Lucent Technologies is suing Microsoft for patent infringement over a technology used in the Xbox 360 game console.

The telecoms giant claims Microsoft is using its patented technology in the Xbox 360's built-in MPEG-2 decoding capability.

At the center of the dispute is Patent No. 5,227,878, "Adaptive Coding and Decoding of Frames and Fields of Video," issued by the US Patent and Trademark Office (USPTO) to Lucent on 19 July 1993.

This is not the first time Lucent and Microsoft have sparred legally over the 5,227,878 patent. In a previous suit filed in 2003, the tables were turned, with Microsoft suing Lucent in an effort to seek a judgment of non-infringement. The company was successful; a judge last year granted summary judgment in Microsoft's favour because of a typographical error in the patent.

Lucent has since corrected the error with the USPTO and received an official patent correction notice. Although Microsoft was awarded a judgment in the previous case concerning the same patent, that did not bar Lucent from taking separate action against Microsoft in the future, Lucent said in court papers.

Before taking its latest legal action, Lucent notified Microsoft of what it believes is "willful' infringement of its patent, but did not cease distribution or production of the Xbox 360, according to papers filed by Lucent.

Lucent is seeking unspecified damages from Microsoft and is requesting a jury trial to resolve the suit.

Neither Lucent nor Microsoft responded to requests for comment on Tuesday.