T-Mobile—and its customers (and investors and lawyers)—has much to gain from combining with Dish. Despite years of edgy advertising and disruptive offerings flown under the marketing banner of “The Uncarrier,” T-Mobile remains stuck in fourth place behind its wireless rivals in terms of subscribers. T-Mobile’s outspoken CEO, John Legere, has long sought to make a big move to help his company compete with his industry’s twin titans, Verizon and AT&T, most recently by moving toward a merger with rival Sprint. That deal was ultimately called off under pressure from regulators.

What Dish offers T-Mobile is a finite resource valuable for big telecoms: Wireless spectrum, a government-regulated resource that carriers need to be able to offer service. Dish was markedly aggressive in snatching up such spectrum during recent government auctions, and now has about $60 billion worth of it. Until now, it hasn’t been clear what Dish was up to—it doesn’t run its own wireless network, so the spectrum was only beneficial to Dish as something valuable to hoard.

But if Dish and T-Mobile merge, T-Mobile would be able to tap into that spectrum, adding more and faster service across the country. That, combined with the continuation of its industry-unsettling “Uncarrer” strategy, could turn T-Mobile into a real threat for Verizon and AT&T for the first time. And because the deal wouldn’t reduce the number of major mobile carriers in the U.S., regulators are more likely to let this merger happen.

What’s in it for Dish? It would finally get to use that $60 billion in spectrum without the costly expensive of building its own wireless network — and start selling broadband data packages, too, moving into a lucrative new market.