Resurgent T-Mobile passes 50M subscribers, but CEO refuses to talk about Apple's 'iPhone 6'

"We have completely reversed T-Mobile's trajectory and started a revolution that is changing the rules in wireless," T-Mobile CEO John Legere said in a release. The quarter marks T-Mobile's fifth consecutive period with over 1 million net subscriber additions.

In comparison, competitors AT&T and Verizon posted net additions of 1 million and 1.4 million subscribers, respectively, in their own fiscal second quarters. Sprint, rumored to be in merger talks with T-Mobile, lost 245,000.

Some 329,000 of T-Mobile's additions were mobile broadband customers driven by tablets, the company noted, a five-fold increase from the previous quarter. T-Mobile sees tablets such as the iPad — as well as wearable devices — as a significant opportunity for growth.

"We're very excited about wearables coming with their own radios, and we're seeing some of these on the horizon," T-Mobile marketing chief Mike Sievert added during Thursday's earnings call.

Despite the rapid increase in tablets, smartphones continued to dominate T-Mobile's hardware sales. The carrier moved 6.2 million smartphones in the quarter, and the devices now account for 83 percent of phones on T-Mobile's branded network.

T-Mobile has the smallest exposure of any major carrier to the iPhone, however. Asked for his opinion on whether the launch of Apple's next-generation handset would have a material impact on the company's subscriber growth going forward, Legere said that such an event would present a "huge opportunity," but was cagey on specifics.

"You're not gonna get me to use the iPhone 6 word on this call," Legere joked.

Apple and T-Mobile have worked more closely in recent months as T-Mobile claws its way back into contention with its larger rivals thanks to a series of "Un-Carrier" initiatives. As part of "Un-Carrier 5.0," T-Mobile offered potential customers a free iPhone 5s with unlimited data to "test drive" the carrier's network for one week.