AT&T's calling its latest 4G LTE network "5G E" isn't just drawing the ire of tech media and fans. It's now drawing fire from Sprint in the form of a lawsuit.

In a lawsuit filed in New York's Southern District, Sprint says it is taking the action as a result of "AT&T’s false advertising and deceptive acts" around 5G E.

Since late last year, AT&T has been touting its upgraded 4G LTE network as 5G E in TV ads, ramping up the running of the spots in 2019.

AT&T, Sprint alleges, "has sought to gain an unfair advantage in the race to 5G by embarking on a nationwide advertising campaign to deceive consumers into believing that its existing 4G LTE Advanced network is now a 5G network."

"This technology is indisputably not 5G," Sprint's suit continues. "Adding an 'E' or the word 'Evolution' to 5G does not mitigate the deception. AT&T is advertising its network as '5G' and consumers wrongly believe that AT&T is offering 5G technology."

In addition to its television campaign, AT&T's website also now has a section for "5G E" phones. This includes phones released last year like the Galaxy S9, iPhone XR and iPhone XS as well as older phones like the Galaxy S8, iPhone 8 and iPhone X.

In updates to its Android phones, AT&T has already changed some devices to display a 5G E logo. A recent beta of iOS 12.2 shows the company is working with Apple to show the indicator on iPhones as well.

In a statement provided to USA TODAY, Sprint says that "AT&T is deliberately deceiving consumers into believing that their existing 4G LTE network operates on a coveted and highly anticipated 5G network."

"The reality is that this network isn’t ‘new’ and ‘5G E’ is a false and misleading term. AT&T is just like Sprint and all the other major wireless carriers currently operating a nationwide 4G LTE network. AT&T’s deceptive ads have harmed consumers by persuading them to purchase or continue purchasing AT&T’s services based on the lie that they are offering 5G."

"It's clear that no other technique has worked," Sprint's outside counsel, Craig Whitney from the firm Frankfurt, Kurnit, Klein & Selz, tells USA TODAY. "We're talking about tens, if not hundreds of millions, of consumers here are being blatantly deceived into thinking that AT&T's LTE network is 5G, which it's not."

In its suit, Sprint says that it reached out to AT&T on Jan. 4 "demanding that AT&T stop its false and misleading activity." On Jan. 16, AT&T responded by "unequivocally denying Sprint’s request and refusing to alter its deceptive conduct," according to the suit.

"We have very extensive evidence to prove that consumers are confused," Whitney says.

AT&T remains defiant

In a statement provided to USA TODAY, AT&T remained defiant while vowing to fight Sprint's lawsuit.

“We understand why our competitors don’t like what we are doing, but our customers love it. We introduced 5G Evolution more than two years ago, clearly defining it as an evolutionary step to standards-based 5G," the company said. "5G Evolution and the 5GE indicator simply let customers know when their device is in an area where speeds up to twice as fast as standard LTE are available."

"We will fight this lawsuit while continuing to deploy 5G Evolution in addition to standards-based mobile 5G. Customers want and deserve to know when they are getting better speeds."

AT&T also took a shot at Sprint's pending $26-billionmerger with T-Mobile, saying that the company "will have to reconcile its arguments to the FCC that it cannot deploy a widespread 5G network without T-Mobile while simultaneously claiming in this suit to be launching ‘legitimate 5G technology imminently.’”

In a filing last year to the FCC about its need for the merger, caught by industry analyst Walter Piecyk, Sprint shared a map highlighting the deficiencies in its LTE network as well as its overall business. Sprint and T-Mobile have argued, during the merger process, that they need each other in order to build out a nationwide 5G network.

In response to AT&T's comment, a Sprint spokeswoman told USA TODAY that while "Sprint will launch mobile 5G service in the first half of 2019 in nine markets across the country," without the merger neither Sprint nor T-Mobile "as a standalone will be able to deliver 5G coverage, capacity, speeds or consistency of experience anywhere near what the new T-Mobile can achieve."

The "New T-Mobile" is the name T-Mobile and Sprint are calling their combined companies during the merger process.

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Not the first carrier to get angry at AT&T

AT&T's other rivals, T-Mobile and Verizon, have each taken exception to AT&T's marketing last month.

T-Mobile called out AT&T on Twitter, sharing a video where it pasted a "9G" sticker on an iPhone writing "didn't realize it was this easy, brb updating." Verizon meanwhile took out a full-page ad in several major newspapers, including USA TODAY, to promise that it "won’t take an old phone and just change the software to turn the 4 in the status bar into a 5."

Sprint says that, by claiming it has this so-called 5G E network in 400 markets when it isn't real 5G, AT&T "seeks to induce consumers to purchase or renew AT&T’s services when they might otherwise have purchased Sprint’s services."

In addition to asking for AT&T to be blocked from using "5G E" or its related terms now and going forward, Sprint is seeking damages from AT&T over the "immediate and irreparable harm" the ads, it says, have caused the company to suffer by making it appear as if AT&T's products and devices are superior to Sprint's.

There is no specific dollar figure requested, with Sprint's lawyers requesting for an amount to be "determined at trial."

Follow Eli Blumenthal on Twitter @eliblumenthal