CBS just threw down the gauntlet: Dish Network subscribers will lose access to CBS-owned stations Thursday at 7 PM ET if the companies can’t agree to terms on a new carriage deal. The broadcaster says that after six months of talks, Dish has “not been operating with the same sense of urgency” to make a deal.

“In the last few weeks, we have granted two extensions, in the hopes that this would give both parties sufficient time to come to a resolution,” CBS says. “The second extension, which protected Dish subscribers’ programming over the Thanksgiving holiday weekend, was the final one.”

Dish customers stand to lose access to CBS outlets in 14 cities including Los Angeles, New York, Chicago, San Francisco, Boston and Detroit. There’s a possibility that an impasse also could endanger carriage of some CW and independent stations and cable networks including Showtime and CBS Sports Network. CBS has a website that urges viewers to lobby Dish to make a deal — though it doesn’t provide information about the terms under discussion so outsiders can assess whether the networks’ demands are reasonable. The site also offers help for those who want to switch providers.

Dish said last month that “only CBS can force a blackout of its channels” and that it was “actively working to reach a deal before the contract expires.” Chairman Charlie Ergen told analysts recently that CBS’ decision to stream its stations’ programming — except for major sports including NFL football — for $5.99 a month via CBS All Access “makes that product less interesting” for pay TV distributors. But he praised CBS’ high ratings and “marvelous job with content creation. I think they’re the best at that, have been the best at that and certainly are a valued partner, so I would certainly think that you’ll see them on Dish.”