T-Mobile's (NASDAQ:TMUS) aggression continues unabated. The magenta carrier unveiled Un-carrier 5.0 and 6.0 earlier this week, just hours after Amazon.com unveiled its Fire Phone. When combined with the four previous Un-carrier initiatives, there are a lot of reasons to switch to T-Mobile.

Test Drive is exactly what it sounds like. Prospective customers can get a free iPhone 5s and use it on T-Mobile's network for a week, with Apple providing the devices for free. T-Mobile says that 12,000 people have signed up for Test Drive in the first 24 hours. Music Freedom exempts eight of the most popular music streaming services from counting toward data caps.

One important benefit of Test Drive is that there are no explicit financial costs to T-Mobile, unless it pays Apple for any damage done to the loaned units. Compare that with T-Mobile's early termination fee offer, which cost $100 million last quarter. Test Drive is an important vote of confidence in T-Mobile's network strength, as it has caught up quickly with larger rivals. It even beat AT&T and Verizon to deploying VoLTE, which is an important shift in the industry.

T-Mobile is spending heavily to acquire new customers, but that momentum will likely pay off in the long run as churn continues to decline.

In this segment of Tech Teardown, Erin Kennedy discusses T-Mobile's tactics with Evan Niu, CFA.

(Relevant segment begins at 2:56.)