T-Mobile USA today reported holiday-quarter earnings. Among the highlights: The carrier lost 802,000 contract customers because it did not get to carry the iPhone, thus contributing to its 3.3-percent quarterly revenue decline down to $20.6 billion. The Deutsche Telekom-owned carrier also said it would embark on a major network transformation this year and promised to launch 4G LTE network sometime in 2013.

The Bellevue, Wash.-headquartered firm hoped the failed AT&T merger would solve capital expenditure issues, so it did not invest in network infrastructure. The strategy backfired as T-Mobile USA is the last major United States carrier to begin 4G LTE deployment. The company’s CEO & president Philipp Humm talked his reinvigorated challenger strategy for getting the business back to growth in a conference call with Wall Street analyst.

The initiative includes a $4 billion investment over time into network modernization and LTE deployment, representing approximately $1.4 billion in incremental network investment over the next two years. The company expects to reach broad deployment of LTE with service in the majority of the top 50 markets and 20 MHz service in 75 percent of the top 25 markets.

More highlights are after the break.

T-Mobile will also take advantage of extra spectrum acquired from AT&T and re-farm existing frequencies, reducing the amount of 1900 MHz PCS spectrum used for GSM to deploy HSPA+ in the PCS band and to make room in the AWS band for LTE. Deploying HSPA+ in the PCS band will “harmonize” its spectrum bands with the United States market and international carriers. In the meantime, the carrier will continue to expand its HSPA+ footprint that now covers “well over 200 million people.” In an effort to cut high churn, T-Mobile is also increasing investment in attracting new customers and retaining loyal ones.

It will double down on business customers, remodel retail outlets, ramp up advertising spending and work harder to attract new MVNO partners. New antenna integrated radios will deploy on many of its cell towers, resulting in higher performance and better coverage. All these initiatives will need more workforce, so T-Mobile is going to hire a thousand new workers. There is also a mention of brand relaunching.