Sprint has filed lawsuits against four cable companies, alleging that they have infringed 12 of its patents covering the transmission of phone calls over digital lines. Bloomberg is reporting that the carrier has lodged complaints against Time Warner, Comcast, Cox, and Washington Post-owned Cable One. The carrier is using some of the same patents it employed in its case against VoIP provider Vonage back in 2007 — Sprint won, costing Vonage $80m. All four cable companies have declined to comment on the case, and it's not yet clear what Sprint is seeking in damages.

The carrier's timing is interesting, as three of the four defendants have been cosying up with rival carrier Verizon over the past month. Deals between Verizon and the SpectrumCo consortium which includes Time Warner and Comcast, as well as a separately negotiated deal with Cox, have given the carrier access to AWS spectrum in a number of new markets. This is set to be used in the expansion of its LTE network, and in exchange the cable companies are able to resell Verizon's wireless service. While there's not a direct correlation, it seems more than coincidental that these claims have been filed years after the underlying patents were proven in court.