Clearwire, of course, is a likely recipient of some of Sprint's new capital. Prusch was particularly enthusiastic about Softbank's preference for time-division long-term evolution, or TDD-LTE, wireless broadband technology on 2.5 gigahertz spectrum, which is the same setup that Clearwire has deployed.

However, Prusch and CFO Hope Cochran had less to say about a potential refinancing, or other situations that could involve Sprint investing its new capital in Clearwire.

Walt Piecyk of BTIG LLC noted during the call that, with favorable debt markets, Clearwire could improve its position by refinancing ahead of December interest payments.

"If you're not taking advantage of that now, shouldn't that imply that there's another source of capital that is about to happen?" Piecyk asked.

"You're right to notice that we're in a strong cash position at the moment, and the debt markets are interesting, as well as we've had good movement in our debt recently," Cochran said. "We continue to stay close to the market and watch our opportunities there."

Clearwire has about $4.2 billion in long- term debt. In December, the carrier can redeem much of it. Sprint could lend the company money at a lower rate, among other options.

Sprint has already received $3 billion in capital from Softbank, and will get $5 billion more next year. The Overland Park, Kan., operator has provided Clearwire with funds in the past, and is increasing its stake in the company by purchasing shares from founder Craig McCaw.

Cochran also declined to reveal whether Clearwire is shopping spectrum, perhaps to pay down its $4.2 billion in long-term debt.

The company has the ability to sell spectrum, she said, but would need approval from 10 of 13 board members if it exceeds certain thresholds.

"If we were to sell spectrum, we can use the proceeds to pay back debt and it would need to go to all of the debtholders equally within that class," she said, "so we would need to be careful of that."

Clearwire said that its $1.2 billion in cash at the end of the quarter would keep the business running for another 12 months.

The company has dramatically scaled back its scheduled deployment of LTE sites on its network, to 2,000 sites by June 2013 from 5,000 sites.

Clearwire said that it ultimately plans to deploy 8,000 sites, which it expects to cost $600 million.