UPDATE: Negotiations continued Saturday between Viacom and AT&T, officials told USA TODAY. The Viacom channels remained on AT&T's platforms past the Friday deadline. On Saturday, Viacom updated its KeepViacom.com website with this message: "Thank you for your patience as we work to reach an agreement with AT&T-DIRECTV to keep Viacom channels on the air."

DirecTV customers may soon find themselves with fewer channels.

At midnight Friday, the contract between AT&T and Viacom is set to expire, meaning popular stations such as Nickelodeon and Comedy Central could go black.

Viacom is warning AT&T's DirecTV subscribers that they may lose access to 23 channels if a dispute over fees isn't resolved before the contract expires. Viacom also is encouraging customers to contact AT&T.

"Unfortunately, AT&T is abusing its new market position by favoring its own content – which significantly underperforms Viacom’s – to stifle competition," Viacom said in a statement Tuesday.

However, AT&T is hoping "to avoid any interruption to the channels some of our customers care about," the company told USA TODAY in a statement late Tuesday.

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“We’re disappointed to see Viacom put our customers in the middle of their negotiations," AT&T said in the statement. "We are on the side of customer choice and value and want to keep Viacom’s channels in our customers’ lineups."

The channels that could be impacted are six Nickelodeon channels, six MTV channels, and five BET channels, as well as Comedy Central, Paramount Network, CMT and CMT Music, TV Land, Logo, VH1, and Spanish-language service Tr3s, AT&T posted on its website.

AT&T is the largest pay TV provider in the U.S., with 24.5 million subscribers.

Viacom is posting updates on its website, www.keepviacom.com, and airing ads that urge customers to contact AT&T. The media company has done the same in other contract negotiations.

Trevor Noah, host of Comedy Central’s "The Daily Show" stars in one of the ads.

“If you think government shutdowns are bad, get ready for something worse," Noah said. "AT&T-DirecTV might drop Comedy Central and up to 22 other Viacom channels."

In its statement, Viacom says it is "the No. 1 cable family serving key customers and communities on AT&T-DirecTV’s services across kids, teens, 18-49, African Americans and Hispanics."

AT&T said “several of Viacom’s channels are no longer popular.”

“Viacom’s channels in total have lost about 40 percent of their audience in the past six years,” AT&T said in the statement. “Viacom is a serial bad actor in these business negotiations and has repeatedly used these tactics with other distributors.”

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What's next?

Disputes between content providers and cable and satellite providers aren't uncommon as companies try to negotiate new deals.

Both AT&T and Viacom say they are looking for a resolution.

"We have made a series of offers that are good for consumers and good for AT&T – giving subscribers more access to the Viacom channels they love, including Nickelodeon, BET, MTV, Comedy Central and Paramount, while enabling AT&T-DirecTV to lower customers’ bills in the process," Viacom said.

AT&T said it's also the company's goal "to deliver the content our customers want at a value that also makes sense to them.”

“We’ve always fought to get the best deal for our customers, delivering the content they want at a great value," AT&T said. "We’ll continue to fight for that here.”

Sometimes the negotiations are extended to allow the parties to reach an agreement. In many situations, the stations don't go black.

One ongoing dispute that has lasted several months is between Dish Network, HBO and Cinemax.

HBO and Cinemax went dark for Dish Network subscribers in November as part of a programming dispute between Dish and AT&T, owner of the two premium cable companies.

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Contributing: Eli Blumenthal

Follow Kelly Tyko on Twitter: @KellyTyko