Microsoft has been hit by the largest patent fine in history after a San Diego jury ruled that Windows Media Player infringed Alcatel-Lucent's patents.
Microsoft was ordered to pay Alcatel-Lucent $1.52bn (£770m) for using MP3 technology without a licence, almost triple the $612m (£311.78m) that BlackBerry maker RIM paid to NTP in March 2007.
The jury awarded damages of $769m (£391.76m) for each of the two patents that were found to be infringed.
Kirkland & Ellis litigation star John Desmarais acted for Alcatel-Lucent against Fish & Richardson's John Gartman.
The decision, which Microsoft will appeal, will worry other companies that use MP3 technology.
Microsoft deputy general counsel Tom Burt said in a statement: "We think this verdict is completely unsupported by the law or the facts.
"We are concerned that this decision opens the door for Alcatel-Lucent to pursue action against hundreds of other companies who purchased the rights to use MP3 technology from Fraunhofer, the industry-recognised rightful licensor."
Microsoft argued that it had already paid $16m (£8.15m) to license the technology from Fraunhofer, which developed the MP3 technology with Bell Labs. Last year Alcatel acquired Lucent Technologies, which owns Bell Labs.
Microsoft has hit back with several patent counter-claims pending in the International Trade Commission.