Masayoshi Son, president of Softbank, left, and Dan Hesse, chief executive officer of Sprint Nextel, smile during an interview in New York on Oct. 18. (Scott Eells/BLOOMBERG VIA GETTY IMAGES)

Sprint Nextel took the next step in a comeback bid Monday, announcing a $2.2 billion takeover of wireless carrier Clearwire to better compete with big rivals just one year after analysts had all but written it off.

The acquisition would significantly boost Sprint’s stock of airwaves for building out a high-speed 4G mobile network like those already offered by industry leaders Verizon Wireless and AT&T. The deal is only possible through the $20.1 billion purchase of Sprint by Japan’s SoftBank, a deal still under consideration by federal regulators.

The complex strategy by Sprint is one of several multibillion-dollar bets in recent months by companies including Deutsche Telekom and Dish Network. They are eager to establish a footprint in the world’s most lucrative wireless market, where U.S. consumers show no end to their appetite to watch videos, surf the Web and post photos on social networks over smartphones and tablets.

It’s also the latest step in Sprint’s arduous journey to overcome a massive accumulation of debt and a decline in subscribers. Chief executive Dan Hesse took over five years ago aiming to reverse customer losses and fight off an attempted merger by rivals AT&T and T-Mobile that would have left Sprint little room in the marketplace.

“It was like trying to catch a falling knife,” Hesse said in a recent interview, describing the first five years of his tenure. “Now, we are in a stronger position than ever. Finally.”

The purchase of Kirkland, Wash.-based Clearwire and SoftBank’s acquisition of Sprint are expected to win approval by federal regulators, who will review both deals, analysts said. Sprint is buying the remaining 49 percent of Clearwire that it doesn’t already own, which gives it full control of the company’s nationwide spectrum.

The Federal Communications Commission and the Justice Department have signaled a desire to bolster smaller rivals of AT&T and Verizon Wireless, the two giants that together control 70 percent of the market. Sprint and T-Mobile are positioned as lower-cost alternatives to the bigger firms.

Sprint continues to face massive challenges, analysts say. Even with an infusion of money from SoftBank, Sprint will have less cash and more debt than its high-powered rivals. AT&T and Verizon already have their 4G networks up and running in many major U.S. cities. Most customers are already committed to a carrier, which means Sprint would have to steal away subscribers through promises of lower prices. It made a $15 billion deal with Apple to carry the iPhone, a bet that some analysts doubt is worth the payoff.

“It’s still going to be a tough row to hoe,” said Jeffrey Silva, an analyst at Medley Global Advisors. “Sprint is better-positioned now than they have been in many years, but it’s really hard to make great leaps in the wireless market because it is saturated at this point.”

It’s a dramatic turn of events for a company that as recently as spring 2011 was treading close to collapse.

In March of that year, Hesse was in an Orlando hotel room, pacing the floor as he rehearsed a keynote speech for the wireless industry’s annual conference, when he received a call that would throw his company back into tumult.

An aide called to say AT&T made a $39 billion bid to buy the fourth-largest carrier, T-Mobile.

Sprint had finally reached a point of some stability after cost-cutting and improved customer service. Its stock hit a plateau of $4 a share from a low of less than $1.50 at the end of 2008. The company had decided to retire the walkie-talkie technology network it acquired through its disastrous $35 billion purchase of Nextel in 2004, a small boost of confidence to weary investors.

Hesse was about to appear on stage before thousands of executives, investors and analysts for the CTIA wireless industry conference. Everyone in the room would want to know his reaction to the AT&T deal, he said. He feared the merger would concentrate power in the hands of the biggest wireless firms and make it even harder for Sprint to survive.

“I knew I had to come out strong against the merger; it was a deal that would create a duopoly and was bad for the entire ecosystem,” he said.

From then on, in Hesse’s speech and through Washington lobbying, Sprint turned much of its attention for the next year toward fighting the deal.

In a Senate antitrust judiciary subcommittee hearing in May, Hesse sat alongside the top executives of AT&T and Deutsche Telekom, the owner of T-Mobile, and warned that the merger would make it impossible for Sprint to survive as a stand-alone firm.

Lawyers for Sprint blasted the FCC with hundreds of pages of technical and economic papers saying the deal would hurt consumers. Sprint hired public relations firms and created coalitions with public interest groups to slam the transaction.

It’s unclear how much influence Sprint had on the decisions by Justice and the FCC. But both agencies pointed to concerns over Sprint’s future as a reason to reject the deal.

Today, FCC Chairman Julius Genachowski credits his decision to reject the AT&T merger with T-Mobile with putting Sprint in a position to attract investments from Japan’s SoftBank.

“The mobile marketplace two years ago was on the doorstep of duopoly. But our rejection along with the Justice Department of the proposed AT&T-T-Mobile deal, and other pro-competition actions we’ve taken, have led to an improving competition picture in the United States,” Genachowski said in a recent speech at the Council for Foreign Relations.

SoftBank operates on the same technology as Clearwire, which could make it easier for Sprint to negotiate with handset makers for exclusive deals. And Hesse said he intends to keep Sprint’s unlimited data plan, instead of making the most active customers pay more for higher levels of service, as other companies do.

Those moves, analysts say, could be positive for consumers.

“A revitalized Sprint would put pressure on the whole industry to be more innovative and maybe even price sensitive,” said Paul Gallant, an analyst at Guggenheim Securities.

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