In what is probably a direct response to Sprint's lawsuits against Comcast and other cable companies filed in December, Comcast filed suit on Friday in the US District Court for the Eastern District of Pennslvania against Sprint, alleging infringment of four of its patents.
The patents are US 6,112,305, Mechanism for dynamically binding a network computer client device to an approved internet service provider, US 5,987,323, Starting a short message transmission in a cellular communication system, US 6,885,870, Transferring of a message, and US 7,684,391, Communications system for delivering multimedia internet protocol packets across network boundaries.
Being neither a communications technology or IP expert, I have no idea what the significance of these specific patents might be, but this is not an unusual response in this type of patent dispute. Sprint's lawsuits were filed shortly after Comcast and other cable operators announced they were selling their wireless spectrum to and entering into a joint marketing agreement with Verizion Wireless, a deal that could alter the competitive landscape in the communications market. That move also signaled the ending of Comcast's reselling agreement with Clearwire, in which it still holds a minority stake. Sprint holds a majority stake in Clearwire.
The case number is 2:12-cv-00859. More information can be found on Pacer (registration required and fees may apply).