Patent powerhouse Intellectual Ventures Management LLC (IV) is using its intellectual property holdings to go after AT&T Inc. (NYSE: T), Sprint Corp. (NYSE: S) and T-Mobile US Inc. , claiming the U.S. wireless operators infringed on 12 network-related patents.

The complaint, filed in the U.S. District Court of Delaware, alleges that the three carriers infringed on patents related to features such as call completion when roaming on other networks, data transmission and message prioritization. The suit is seeking unspecified damages.

Verizon Wireless was spared, because it is already a licensee of IV.

Why this matters
While handset makers and operating systems have been the more high-profile subjects of recent IP lawsuits, the wireless operators aren't immune to the courtroom. IV, run by former Microsoft Corp. (Nasdaq: MSFT) CTO Nathan Myhrvold, has come under fire for its practice of hoarding patents (it has more than 35,000) and using them to extract licensing fees from technology companies. But it's also been quite successful at doing so.

The firm tells AllThingsD that it would prefer to work out a business relationship with the three wireless operators, but the companies have so far been unresponsive, increasing the likelihood of a courtroom showdown.

For more
Read up on patent litigation in the wireless industry.

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• Intellectual Property Boom
• ITC Makes a Moto/Microsoft Ruling
• Making Sense of the Handset Patent Plays

— Sarah Reedy, Senior Reporter, Light Reading Mobile