T-Mobile guarantees to top trade-in offers made by Verizon, AT&T and Sprint
6

T-Mobile announced today that it would top trade-in offers made by Verizon, AT&T and Sprint, for used smartphones and tablets. The offer starts on September 17th, and will run for a limited time. Within seven days of completing a trade at T-Mobile, contact the carrier if you see a higher trade-in price than the one you were given at T-Mobile. Call, or go online, and report when and where you received the higher price. And you need to also pass along the amount of the higher offer.
source: T-Mobile
Once T-Mobile verifies the higher offer, it will not only match what Verizon, Sprint or AT&T would have paid you for the trade, they will also provide you with a $50 bill credit. The credit will appear within two to three bill cycles. T-Mobile says that it will track the trade-in market daily to make sure that it is offering its customers the best trades.
"We’re going to see some of the most phenomenal devices ever in the coming months, and that means a whole lot of Americans trading-in their devices and upgrading. For years, the big carriers have been ripping off their customers with low-ball trade-in values, so we’re putting an end to that and guaranteeing we’ll give customers what they deserve − the best value in the industry."-John Legere, CEO, T-Mobile
source: T-Mobile
Things that are NOT allowed: