"Anybody here from New York? Any of you use AT&T? Any of you that use them, you happy? Of course not, the network's crap."

And with those fierce words from freshly-minted CEO John Legere at CES this January, T-Mobile's new offensive — a coordinated barrage against rivals several times its size — kicked off, bolstered today by its complete elimination of the two-year contract and the long-awaited introduction of the iPhone. "You'll see some swagger, you'll see some attitude, you'll see some aggressive attacks on our competition... all in fun, of course." The language was even fiercer at today's event.

"In fun"? Perhaps, but Legere wasn't joking. AT&T and T-Mobile have taken off the gloves in recent months, directly attacking each other's networks in a series of ads and statements. And T-Mobile's attitude isn't entirely unwarranted: since parent company Deutsche Telekom's sale of the American unit to AT&T fell through, Legere's company has amassed desperately-needed spectrum. AT&T famously quipped in 2011 that T-Mobile had "no clear path" to deploying LTE, but thanks to some shrewd business deals, hand-me-down spectrum licenses from both AT&T and Verizon, and aggressive jockeying of existing airwaves, the carrier now indeed has a very clear path to a next-generation network. Its first LTE markets officially roll out this month, with 200 million people to be covered by the end of the year. And the MetroPCS merger, which will beef up both spectrum and subscriber count even further, is close to a done deal.

Going on the defensive against T-Mobile is unfamiliar territory for AT&T, which has traditionally focused on matching Verizon — more evenly positioned with AT&T on subscriber count, pricing, technology, and coverage — tit for tat. There's something about T-Mobile's newfound "swagger," as Legere puts it, that seems to have the American wireless industry on edge.

Of course, for David, getting Goliath's attention is only half the battle; now you've got to take his customers. While it's remained profitable, T-Mobile continues to bleed postpaid customers each and every quarter.

Sprint would tell you it's not easy. CEO Dan Hesse had to spend billions to secure the iPhone, which has now become less of an advantage for a carrier and more of an equalizer — a subscriber stop-loss — in the half decade since its introduction on AT&T. In the quarters since, Sprint has added less than a million net subscribers. No one is switching carriers to get the iPhone.

"I think we've already seen the end of device exclusivity for the really big phones. It's certainly the case for the Galaxy S series, and I'd argue it's been the case for the iPhone too for some time," says Jan Dawson, chief telecoms analyst for research firm Ovum. "Recent [exclusives] like the Lumia series at AT&T really haven't made much of a dent, and the few other ones like the Droid DNA are more about branding than they are about having totally unique experiences."

So if the iPhone isn't going to bring subscribers to T-Mobile in droves, what will? Is it the banishment of the ubiquitous two-year contract combined with the monthly payment plan for new phones? It's an interesting talking point, but might not have much practical impact for the average customer. "Consumers just don't know how much phones really cost, and when you try to talk to them about alternative ways of paying for devices, their eyes start to glaze over pretty quickly," Dawson says, noting that T-Mobile has been offering this structure for a while — the only thing that's new is that T-Mobile is now eliminating the old contract model entirely.

Ultimately, it might come down to old-fashioned dollars and sense. If you're picking up a new phone, you'll pay more per month thanks to T-Mobile's monthly payment plan than you would if you didn't buy hardware, granted, but other carriers don't offer the inverse (discounting plans for not buying new hardware). At $70 for unlimited data, T-Mobile undercuts Sprint, AT&T, and Verizon considerably, and it doesn't hurt that it's got a brand-new LTE network that it promises to ramp up quickly.

But will people know this is all happening? If today's event is any indication, Legere — who has an unfiltered vocabulary and a charisma rarely seen in this business — has every intention of getting the word out.