Today Intellectual Ventures (IV) filed a patent infringement complaint against AT&T, Sprint and T-Mobile in the U.S. District Court of Delaware. The privately held patent holding company co-founded by a former Microsoft Corp executive, accused AT&T, Sprint Nextel (S.N) and T-Mobile USA of fifteen counts of infringements of patents related to their wireless network services.

IV said that the operators had infringed on its patents either alone or in conjunction with each other through their interoperability agreements including those involving swapping of multi-media messages between their customers.

"The wireless communications networks of AT&T, Sprint and T-Mobile use a variety of important technologies covered by Intellectual Ventures' patents. We previously attempted to discuss licensing options with each of these companies, but none were responsive. We filed a complaint for infringement today in the U.S. District Court of Delaware to get these three companies on a course toward compensating IV for the value of the inventions they use in delivering their wireless services," said IV?s chief litigation counsel Melissa Finocchio.

In October, Intellectual Ventures also sued Motorola Mobility over several patents."