Feb 16, Reuters - Intellectual Ventures, a privately held patent holding company co-founded by a former Microsoft Corp executive, sued three of the four top U.S. mobile providers for patent infringement.

The company accused AT&T Inc, Sprint Nextel and T-Mobile USA of fifteen counts of infringements of patents related to their wireless network services in a lawsuit it said it filed at the U.S. District Court of Delaware on Thursday.

It 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.

Intellectual Ventures -- co-founded by Nathan Myhrvold, Microsoft's former chief technology officer -- said that Verizon Wireless, the biggest U.S. mobile provider, was not included in the lawsuit as it already has license to use Intellectual Ventures' technologies.

AT&T declined comment for the story while representatives were not immediately available at Sprint and T-Mobile USA, a unit of Deutsche Telekom . Verizon Wireless is a venture of Verizon Communications and Vodafone Group Plc .

(Reporting By Sinead Carew; Editing by Phil Berlowitz)