Cox Communications is suing former business partner Sprint for patent infringement, a countersuit aimed at deflating a patent suit Sprint filed against Cox and three other companies last December. 

The cable company claimed in a complaint filed in a Delaware district court on Monday that Sprint had violated two of its patents related to encoding digital program guides and video transcoding. It wants a permanent injunction against Sprint products and services related to the two disputed patents. 

It also asked the court to declare the 12 patents named in Sprint's December complaint invalid, unenforceable or covered under its existing contracts.  

"We are prepared to aggressively defend ourselves against Sprint’s allegations that we believe have no merit," a Cox spokesman said. "In addition, we will defend Cox’s valuable intellectual property using the appropriate legal channels."

Sprint declined to comment on the case.

The two companies' relationship soured late last year after Cox stopped using Sprint to provide wireless service to its cable customers and decided to sell its AWS spectrum to Verizon Wireless, a wide-ranging transaction that allowed it to sell Verizon's service in its own stores.

The three other companies that agreed to sell their AWS spectrum to Verizon, Time Warner Cable, Comcast and Bright House Networks, also signed exclusive deals to sell Verizon's wireless service, arrangements that will eventually end their existing contracts with Sprint. 

One week after Cox forged the spectrum and marketing deal with Verizon,  Sprint sued Cox, Comcast, Time Warner Cable and one other company not affiliated with the Verizon deal for violating its patented voice call routing technology. 

Sprint asked the companies be banned from selling services that infringe on its patents, including Time Warner's Digital Home Phone and Comcast's XFinity Voice.

In its latest complaint, Cox said it still held contracts with Sprint and was not told about the intellectual property issues until after the companies had signed their agreement. 

"Sprint did not inform Defendants of its pursuit of patent protection until well after the contractual relationships were in place," Cox said.

The FCC is still reviewing the AWS sale between Verizon and its four cable partners. Sprint, a vocal opponent to AT&T's takeover of T-Mobile USA, has expressed concerns about the deal but stopped short of asking the government to block it. 

T-Mobile, MetroPCS and the Rural Telecommunications Group have asked the FCC to stop the transaction.