The telecom industry is becoming fiercely competitive, not just because of the rising threat from Mobile Virtual Network Operators (MVNOs) and cable operators, but also because the overall customer base is not growing at the same clip as before. Add to that the fact that customers are growing weary of the Big Three due to rate hikes and it's easy to see why they are desperate to lock users into long-term commitments. T-Mobile previously made a couple of changes to make customers stay longer and is now running a new promo.The Mobile Report has learned that the carrier is targeting customers who don't currently finance devices through a new deal. The promo will let those customers save $830 on a new flagship phone if they trade in an old device. Though there's a trade-in requirement, customers will be delighted to know that even phones as old as the iPhone 11, Samsung Galaxy S10, OnePlus 9 Pro, and Pixel 6 qualify. It doesn't matter if the device is broken.The catch here is that customers who go for the deal will have to stay with T-Mobile for two years. But then again, this is the whole point of the promo. T-Mobile doesn't want to lose customers who aren't bound to it already.