T-Mobile CEO John Legere. Source: T-Mobile.

We're not quite all the way through T-Mobile's (NASDAQ:TMUS) third quarter yet, but that didn't stop the so-called Uncarrier's CEO, John Legere, from opening up about subscriber growth at the Goldman Sachs Communacopia Conference last week.

He noted at the conference (and later through an SEC filing) that T-Mobile managed to match or surpass the same amount of branded net customers from the previous quarter (which was 1 million), as well as branded postpaid phone net additions (which was 760,000). Hitting those high numbers for a second consecutive quarter is a pretty impressive accomplishment and it comes as there's just under two weeks still left in the quarter.

T-Mobile mentioned earlier in September that it would beat the 2.1 million net subscriber additions from the previous quarter, but Legere's comments went even further. He mentioned that T-Mobile had exceeded branded prepaid net customer additions from Q3 2014 (which were 411,000) and has tripled the amount of branded prepaid net customer adds from Q2 2015.

I just threw a lot of numbers and prepaid/postpaid terms out there. So what does all of this actually mean? In short, it shows that T-Mobile is continually growing is subscribers at a very aggressive rate.

The second quarter of 2015 marked the ninth consecutive quarter that T-Mobile added 1 million or more total customer additions -- and with Legere's admissions last week it now makes 10 consecutive quarters.

All of this subscriber growth has has helped T-Mobile jump from 11% market share when Legere first started about three years ago, to 17% now.

What's next
Heading into Q4 2015, there's still plenty for T-Mobile to look forward to. The company just launched a Lifetime Coverage Guarantee for Extended Range LTE devices (like the new iPhones and top-of-the line Samsung phones). The new option allows new and existing users to return their devices and receive a free month of service if they're not completely satisfied with their coverage.

The option could help T-Mobile in two ways. First, if offers new subscribers a low-risk way to get their hands on the new iPhone 6s and iPhone 6s Plus. Similar the company's former iPhone Test Drive, the Lifetime Coverage Guarantee is yet another way to lower the barrier of getting new customers to sign up for the Uncarrier's network.

Secondly, T-Mobile's rolled out a 700 MHz spectrum in 170 markets, which allows for a better LTE signal across wider areas and inside of buildings. The new iPhone 6s and iPhone 6s Plus are compatible with this spectrum, as are a handful other high-end devices, and more smartphones are adding this capability. As they do, T-Mobile customers should experience better service, at least partially.

This could improve the company's network quality, which is currently ranked the lowest among the top four U.S. carriers. If that happens, T-Mobile will not only be able to boast about its net subscriber additions, but also that it's network quality is more on par with its competitors. And if T-Mobile can reach that point soon, then there will be even more for Legere (and investors) to brag about.