There was a longer line of people waiting outside T-Mobile's flagship store in Times Square to buy the new OnePlus 6T smartphone than there was for the new iPhones.

The OnePlus 6T is the first OnePlus phone sold by a US carrier.

T-Mobile is offering a trade-in deal where anyone can trade in an eligible smartphone for a $300 credit toward the $580 OnePlus 6T model.

That means the OnePlus 6T could cost a mere $280 for those who take advantage of T-Mobile's trade-in deal.

At an event on Monday, OnePlus announced some big news: You'll be able to buy the new OnePlus 6T smartphone at a US carrier store.

The OnePlus 6T comes with high-end design, specs, and performance for under $600, while other top smartphones with similar specs can cost more than $800.

The OnePlus 6T is available to buy from T-Mobile stores nationwide and online starting Thursday, making it the first smartphone from OnePlus sold in a US carrier store. It's a big deal for OnePlus to make its mark in the US market, as a smartphone's popularity usually relies almost entirely on whether it's available from a carrier.

OnePlus fans in and around New York City got a bit of a treat on Monday: They could buy the new $580 OnePlus 6T model at T-Mobile's flagship store in Times Square three days before the smartphone's official release. And to top things off, T-Mobile offered prospective OnePlus buyers the option to trade in their old smartphone for a $300 credit toward the OnePlus 6T, a deal it said would end in about a month.

With the trade-in deal, a person could snag the OnePlus 6T for $280. To be clear, it's possibly the best value for a smartphone in recent memory — and judging by the crowd of people outside T-Mobile's store at 5 p.m. on Monday, I certainly wasn't the only one who noticed.

The screen on the new OnePlus 6T. Antonio Villas-Boas/Business Insider

'I've never seen anything like this'

On Monday, T-Mobile's flagship store in Times Square saw a larger crowd of people waiting to buy the OnePlus 6T than it did for the new iPhones, a T-Mobile employee there told me.

"I've never seen anything like this," the employee said.

The same goes for other Android phones from major companies like Samsung and LG.

Now, to be fair and accurate, new iPhones are available to buy from numerous Apple Stores dotting the city, as well as nearly every carrier store, so it's safe to say that lines of people waiting to buy them are diluted across several stores. If the new iPhones were sold at a single store, as the OnePlus 6T was on Monday, the city would most likely need to shut down several blocks, perhaps even a district or two.

Still, a plucky smartphone company that's significantly smaller than Apple and major Android players like Samsung and LG gave T-Mobile's flagship New York City store its biggest line in recent memory.

The back of the OnePlus 6T. Antonio Villas-Boas/Business Insider

The popularity of the brand is growing to the extent that budding content creators are starting dedicated YouTube channels to talk about OnePlus devices, much like the numerous brand-centric YouTubers who discuss Apple and Samsung devices. (Watch out for the launch of the "OnePlus Hype" YouTube channel, whose creator was waiting in line to buy the new device.)

Others skipped "optional" exams and work to get in line at the Times Square T-Mobile store, and some people had been waiting for three hours by the time I spoke with them around 5:15 p.m.

One man originally from India said he skipped classes at Northeastern University in Boston to travel to New York to get the new OnePlus 6T. His professor supposedly understood.

Another person in line, on vacation from Bogota, Colombia, said that one item on her checklist was to get the OnePlus 6 because her boyfriend has the OnePlus 5T and she liked it, citing its comparatively low price tag as the main draw.

"But then I heard that they launched the 6T," she told me, and the rest was history. By the time this post is published, she's likely to own the latest OnePlus smartphone before most other OnePlus buyers. Her boyfriend was not in line, as he was studying, she said.

One man who owned the Google Pixel 3, a smartphone that was released just a few weeks ago but isn't eligible for T-Mobile's trade-in offer, was unfazed about buying the OnePlus 6T at the full price of $580. (For reference, the Pixel 3 starts at $800.)

He was accompanied by his fiancée, whom he had proposed to hours earlier, after the OnePlus keynote, with the help of company representatives and the OnePlus cofounder Carl Pei himself. She was wearing a hat with OnePlus' slogan, "Never Settle," which seemed appropriate.

Another man, who was accompanying his friends in line, said he could finally buy a OnePlus phone now that the OnePlus 6T is compatible with his network, Verizon. It wasn't clear whether he was switching to T-Mobile to buy the new phone. He said he always wanted a OnePlus phone but couldn't get one because previous models were incompatible.

Pete Lau, the founder of OnePlus, taking selfies with fans at the Times Square T-Mobile store. Antonio Villas-Boas/Business Insider

Overall, those in line cited the quality, software, design, feature set, high-end specs, and comparatively low price of OnePlus devices as the driving factors behind their OnePlus fandom.

But the one element that nearly everyone mentioned was "community." OnePlus fans seemingly have a closer connection with the company behind their mobile device, possibly the most important device in their daily lives. And OnePlus consistently communicates with its fans, with tweets and blog posts often addressing them as "friends."