TiVo countered that Microsoft is trying to help its partner AT&T, which is being sued by TiVo for patent infringement.
Microsoft has sued TiVo, accusing the digital video recorder maker of infringing on the software maker's Internet video technology.
The suit, filed Wednesday in San Francisco federal court, claims TiVo DVRs use Microsoft technology related to purchasing and delivering video and displaying programming information.
TiVo said in a statement that the suit is part of a legal strategy to help Microsoft partner AT&T, which faces a patent-infringement suit filed by TiVo.
AT&T is one of Microsoft's largest customers for its video delivery and recording technology. AT&T uses the software in delivering its U-Verse TV service.
Before filing its latest complaint, Microsoft requested to intervene in the suit against AT&T, TiVo said. Nevertheless, neither that action nor the latest legal move "bear on whether the AT&T products and services that are the subject of TiVo's complaint infringe the patents asserted by TiVo," the company said.
"Rather these actions are part of a legal strategy to defend AT&T," TiVo said in a statement. "We remain confident in our position that AT&T will be found to infringe on the TiVo patents asserted."
While TiVo appears unlikely to seek a settlement with Microsoft, the software maker said Microsoft was open to negotiations. "We remain open to resolving this situation through an intellectual property licensing agreement, and we have initiated discussions to engage TiVo in negotiations," spokesman Kevin Kutz said in a statement e-mailed to InformationWeek.
TiVo, which pioneered the DVR, has aggressively sought to protect its intellectual property in the courts. Along with AT&T, TiVo has sued Verizon, alleging similar patent infringement.
In 2004, TiVo sued EchoStar, claiming the satellite TV company stole TiVo's digital video recorder technology for pausing, fast forwarding, and rewinding live TV shows. A U.S. District Court ruled against EchoStar, and the decision is currently under appeal.
TiVo has licensing agreements with DirecTV Group and most of the cable companies.
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