Most of the country doesn’t have much competition for broadband services. But in some of New York City’s boroughs, particularly Brooklyn and the Bronx, Cablevision and Verizon FiOS fight head to head for residential customers. The battle between the two is often ugly, and with a new lawsuit filed yesterday, it just got uglier.

Here’s the background: Verizon claims that their FiOS networks in New York are entirely fiber-optic. Cablevision runs an ad in that market claiming that Verizon’s networks actually use coaxial cables in part, and are therefore not actually all fiber. Verizon challenged Cablevision’s ads with the National Advertising Board, industry’s advertising self-regulation group. Cablevision, however, is not responding in that NAB process, and is instead filing suit against Verizon.

In the lawsuit, Cablevision is asking for the court to give them the all-clear (a declaratory judgement) to continue airing their ad on the basis that it is true and “exposes Verizon’s false and misleading marketing claim against FiOS.”

So what is Verizon saying that isn’t true? According to Cablevision, Verizon uses coax, and not fiber cable, inside the home in “all or nearly all cases.” Verizon might be fiber to the home, in other words, but not through it — FiOS customers’ routers, cable modems, and set-top boxes are using the same kind of wiring as anyone else’s.

Cablevision also contends that “in certain situations,” Verizon has used ordinary coaxial cable outside the home, as well as inside it, and therefore their all-fiber claims are even more false.

In a statement, Cablevision said, “Consumers deserve to make informed decisions based on facts, and Cablevision is asking the court to intervene to stop Verizon from attempting to continue to mislead the public.”

In their statement, meanwhile, Verizon representatives said, “Cablevision cannot compete with Verizon FiOS, or even come close to providing the Internet speeds and performance available from Verizon’s 100% fiber-optic network. Since their network can’t compete against FiOS, they resort to legal stunts, which we will challenge vigorously.”

Not only is this not Cablevision’s first lawsuit against Verizon, but it’s not even their first one this year. At the end of January, Cablevision sued Verizon over their wifi ads. In that suit, Cablevision claimed that Verizon’s “fastest wifi” ads were misleading, as the two companies offer basically the same service through the same routers.

Both lawsuits are now in progress.

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