T-Mobile is taking up to a $300 hit on each OnePlus 6T phone sold in a bid to excite customers in a slow year for smartphones. While the new OnePlus 6T retails for $579.99, T-Mobile is offering a $300 trade-in for a wide range of other devices—even for ancient OnePlus One models.

"That's not OnePlus. That's us, putting the critical offer out in the marketplace to get people excited," said Jon Freier, EVP of T-Mobile US retail.

Trade in any of these at @TMobile and knock the @oneplus 6T price down to $280. General sales Nov 1 9am. pic.twitter.com/JnqXUwbtXm — saschasegan (@saschasegan) October 29, 2018

It sounds like T-Mobile is really trying to capture that OnePlus magic. The cult smartphone brand has fans and a level of loyalty that other Android brands tend to lack, and T-Mobile wants to bring those fans onto its network—hopefully, with the same level of loyalty. T-Mobile has an exclusive on the 6T "for the life of the device," which typically means about six months in OnePlus-world.

"This is the number one brand people have asked about. People send [CEO] John Legere tweets all the time asking, when are you going to carry this brand? Since this is a big opportunity and really kind of responding to customers' feedback about carrying this, we wanted to go big," Freier said.

Having a high-quality, low-cost phone like the 6T sold by T-Mobile is going to help win over customers from other carriers who may not know OnePlus, but may have seen buying a new phone as a barrier to switching carriers, he added. Other carriers' customers will be able to trade in their phones and upgrade for an unusually low price.

"When you think about all the customers of our competitors out there with Android products, this may be the one thing that puts customers over the edge," he said.

It's Exclusive—Like, Really Exclusive

T-Mobile has a unique model of the OnePlus 6T—its unit has 8GB of RAM, 128GB of storage, and a single SIM slot as opposed to the dual SIMs in unlocked 6T phones. It also comes with pre-loaded T-Mobile apps. So why should potential OnePlus buyers come to a T-Mobile store, other than the price?

Freier says the T-Mobile model was "purpose built" for the T-Mobile network, so that it will get better performance on T-Mobile than the international unit.

"Whereas the global SKU is global, a little bit more of a generalized SKU, this one was built specifically for our network," Freier said.

As for the dual-SIM functionality, T-Mobile hasn't been hearing a lot of demand for that, Freier said.

"We don't get a whole lot of requests from customers today saying, 'I need dual SIMs.' That isn't something we get. But if the customers begin to crave that particular benefit, then of course we'll adjust," he said.

The OnePlus 6T goes on wide sale on Nov. 1 at T-Mobile.