Nine years after Verizon promised to make its high-speed Fios internet service available to every household in New York City, the city sued the company on Monday, saying it had failed to keep that pledge.

In a complaint filed in New York State Supreme Court in Manhattan, the city contends that Verizon is in breach of a 2008 franchise agreement. That contract called for Verizon to build a citywide Fios network by the end of 2014. But, the city says, Verizon has failed to make its service available to at least “tens of thousands” of prospective customers and has refused to accept service requests from many others.

For two years, city officials have been pressing the company to satisfy its obligations, in the hope of avoiding litigation. But the two sides reached an impasse this winter, and on Monday the contentious tone of the standoff became public.

“Verizon must face the consequences for breaking the trust of 8.5 million New Yorkers,” Mayor Bill de Blasio said in a statement. He added that, “It’s 2017 and we’re done waiting. No corporation — no matter how large or powerful — can break a promise to New Yorkers and get away with it.”