Aside from losing the number three spot among U.S. carriers, Sprint's second quarter earnings appeared to show a company in turnaround mode and investors liked what they saw. 

Shares of Sprint were up 10 percent in pre-market trading Tuesday as the carrier beat expectations and raised its forecast for the third quarter. For the quarter, Sprint reported operating income of $501 million on $8 billion in net operating revenues.

Postpaid net subscriber additions hit 310,000 compared to net losses of 181,000 in the prior year quarter. Churn was at an all-time record low for the company at 1.56 percent.

Masayoshi Son, CEO of Sprint's parent company Softbank, acknowledged during an earnings call that he has regained some of the confidence lost after the FCC shot down its proposed merger with T-Mobile.

"Marcelo and I, and our total team of Sprint and Softbank together, now we have a plan to have a big turnaround," Son said. 

Amid a management reshuffle that included the release of current CFO Joe Euteneuer, Sprint is preparing for a massive network improvement project that will include thousands of new macro sites, tens of thousands of new small cells, and the upgrade of all of existing sites to support Sprint's three spectrum bands--850 MHz, 1900 MHz and 2.5 GHz. 

Son made the case that Sprint would follow Japan's lead on network design, taking the opportunity to slam the quality of wireless service in the United States. He said he was very confident that Sprint would be able to create equal or better network with much less capex than its competitors.

"As you may know, Japan has the best network in the world," Son said. "To me, every time I come to the United States, I say this network in this country is not something you should be proud of...It's not just Sprint, it's Verizon, AT&T, T-Mo."

Sprint raised its forecast for fiscal year 2015 Adjusted EBITDA from a range of $6.5 billion - $6.9 billion to $7.2 billion - $7.6 billion. That marked a 12 percent increase over prior guidance. 

Sprint has been working with Softbank and other partners in setting up a leasing company that will finance its devices leased by customers on terms the company called "attractive." The arrangements are expected to be finalized in the coming months, and Softbank is expected to be a minority equity investor in the leasing company. 

And while Sprint's turnaround appears to be very real, the company will need to keep the momentum going as it finally ceded its spot as the nation's third-largest carrier. As of the end of the second quarter, T-Mobile had 58.9 million total customers, while Sprint tallied 57.7 million. 

As of 10:14 a.m. CT, shares of Sprint were still up just less than 6 percent to $3.54.