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Sprint fires off lawsuit at cable giants

The carrier claims Comcast, Time Warner Cable, and other cable companies are using digital phone technology that it owns. And thus we see a further fraying of their relationship.

Sprint Nextel has sued several cable providers over what it claims is the illegal use of its digital phone technology, further fraying an already strained relationship between the carrier and the cable industry.

In separate lawsuits filed yesterday, Sprint alleged that Comcast, Time Warner Cable, Cox Communications, and the Washington Post's Cable One all infringed on 12 patents related to digital phone technology it secured in the '90s.

The lawsuits represent just the latest development in an increasingly rocky relationship. Sprint and the cable providers were once strong allies, partnering up to buy spectrum and resell wireless service, and taking part in an investment in 4G wholesaler Clearwire. The cable companies were also significant customers of Sprint's wireline business.

But in recent years, the cable companies have moved to distance themselves from Sprint. They are no longer Sprint customers, representing a blow to the carrier's landline revenue. The cable providers recently struck a deal with Verizon Wireless to sell their spectrum to the Sprint rival for $3.6 billion. As part of the deal, the cable companies will resell Verizon's 4G LTE service, and end their wholesale agreements with Clearwire.

The cable companies have long provided Internet phone service as part of their "triple play" bundle of phone, video and Internet services. Those services compete more against the larger telcos Verizon and AT&T than the more wireless-centric Sprint.

Representatives from Time Warner Cable, Comcast, Cox, and the Washington Post declined to comment on the lawsuit.

The patents allow companies to use inexpensive and efficient data packets to carry voice traffic, which reduces the cost of phone service and provides the backbone for voice-over Internet protocol technology. The various patents go as far back as 1994.

"Sprint invested significant amounts of time and resources in the technology covered by these voice over packet patents," according to a company representative.

The patents are the same as the ones used by Sprint to extract a $80 million settlement from Vonage, which also delivers Internet phone service.

Updated at 9:38 a.m. PT: to include a comment from Sprint.