Motorola, the target of a patent lawsuit by Microsoft, fired back against the US software giant with a patent infringement complaint of its own on Wednesday.
Motorola said its subsidiary, Motorola Mobility, has filed suit against Microsoft in US District Courts in Florida and Wisconsin alleging infringement of 16 Motorola patents.
Motorola accused Microsoft of patent infringement in its personal computer and server software, its Windows Mobile operating system and the Xbox videogame console.
Motorola's action came a day after Microsoft filed suit against Motorola in Washington state accusing the US handset maker of demanding "excessive and discriminatory" royalties related to patented technology.
That suit came a month after Microsoft accused Motorola of violating its smartphone patents.
Motorola said it had asked the courts in Florida and Wisconsin to stop Microsoft from using Motorola's patented technology and provide compensation for past infringement.
"We are committed to protecting the interests of our shareholders, customers and other stakeholders and are bringing this action against Microsoft in order to halt its infringement of key Motorola patents," said Kirk Dailey, corporate vice president of intellectual property at Motorola Mobility.
"Motorola has invested billions of dollars in research and development to create a deep and broad intellectual property portfolio and we will continue to do what is necessary to protect our proprietary technology," Dailey said.
He said it was "unfortunate" that Microsoft has filed patent infringement litigation against Motorola "rather than entering into comprehensive licensing negotiations."
Microsoft's suit filed Tuesday alleged that Motorola was in breach of an agreement to license patents related to wireless and video coding technologies under "reasonable and non-discriminatory terms and conditions."
Microsoft filed suit against Motorola on October 1, accusing the US handset maker of violating nine Microsoft patents in smartphones powered by Google's Android mobile operating system.
Microsoft supplies its own mobile operating system to handset makers and a new line of Windows Phone 7 smartphones went on sale in the United States this week.
Patent lawsuits are a regular occurrence among technology giants and Motorola is currently suing Apple for patent infringement. Apple has hit back against Motorola with a patent infringement suit of its own.
Apple is being sued by Finnish mobile phone giant Nokia for patent infringement and has fired back with a countersuit against Nokia.
Taiwan's HTC and Apple are also currently suing each other over patent claims involving Android-powered phones.
In June, Canada's Research in Motion, maker of the Blackberry, and Motorola reached a settlement to their long-running patent disputes.
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