T-Mobile's doing even more to try prying wireless customers away from Verizon and AT&T. At this morning's Uncarrier 9.0 event, John Legere announced the "Un-contract," a commitment on T-Mobile's side that guarantees customer bills will go down, but never increase unexpectedly. "I'm bringing back the contract," Legere said on stage. But unlike the long-term agreements that T-Mobile phased out long ago, Legere described this one as a reverse contract — from T-Mobile to you. It also locks in all previous Uncarrier movements and data packages as permanent. "I'm guaranteeing those rates for as long as you're a customer," Legere said on stage. The Un-contract goes into effect starting March 22nd, and T-Mobile says it will also protect unlimited data plans from higher pricing.

You can keep your existing Simple Choice plan and we won’t raise your rates. As part of this commitment, customers on existing Simple Choice promotional plans − like the Un-carrier’s ultra-popular 4 lines for $100 with up to 10 GB of 4G LTE data − can keep them for as long as they’re T-Mobile customers. And, if you have an unlimited 4G LTE plan, you can rest assured your rates won’t change for a minimum of two years. You can even change to other qualifying plans and The Un-contract guarantee kicks in again. And you can even leave when you like.

Further, Legere announced "Carrier Freedom," a new program that expands on the company's previous "we'll pay your ETF" offer to cover up to $650 in any payments you currently owe Verizon and AT&T. That's per line, and T-Mobile says it will extend Carrier Freedom to cover up to 10 lines. With this change, T-Mobile is going after people who may feel tied to upgrade plans on AT&T's Next and Verizon Edge. You'll still need to trade in your current smartphone and buy a new handset from T-Mobile if you want to qualify, though.

Previous T-Mobile Uncarrier announcements have included Music Freedom, which allows customers to stream popular music services without it counting against their data plan, and a Jump early upgrade program that led T-Mobile's rivals to roll out their own alternatives. More recently, Legere unveiled Data Stash — or rollover data — which tacks any unused data from a customer's billing cycle onto future months. T-Mobile has also discarded long-term service contracts, added complimentary overseas data coverage, and allowed potential customers to test out its network for a week.

Verge Video archive: John Legere, T-Mobile's eccentric CEO, at Uncarrier 5.0 (2014)