Back in December, Sprint sued Comcast, as well as Time Warner, Cox, and Cable One over 12 telecommunications patents that it successfully asserted against Vonage back in 2007. Probably in response to that suit, Comcast's on the offensive, filing against Sprint first in Philadelphia on Friday, and again in Delaware on Tuesday. The newest cases revolve around two sets of four telecommunications patents, including one for "transferring of a message" and another for a "telephony network optimization and system." In the complaint filed on the 21st, Comcast's attorneys claim the company "has been irreparably harmed by that infringement and will suffer additional damages” unless the court takes action. The lawsuits follow Comcast ending its deal with Sprint and Clearwire to sell 3G and 4G services in favor of partering with Verizon. That may mean there's still some bad blood between the two companies, making it just a little harder to expect this patent skirmish to end like so many others: with a cross-licensing agreement.