Sprint Nextel Chief Executive Dan Hesse said that the carrier will continue to offer an unlimited data plan for the iPhone, telling CNET that the data plan is the company’s “distinctive differentiator.”

He told CNET reporter Roger Cheng that he doesn’t anticipate that the unlimited plan model will change any time soon, saying that it’s a “marriage made in heaven.”

The company announced its earnings Wednesday, posting a loss overall with a small gain in revenue. According to the company, Sprint sold 1.5 million iPhones last quarter — nearly half, 44 percent, to new customers.

Those numbers were still outstripped by competitors who reported slower iPhone sales — AT&T with 4.3 million and Verizon’s 3.2 million.

Still, as GigaOm’s Kevin Fitchard notes, 1.5 million is not a bad figure for Sprint, especially considering that the number-three carrier is about half the size of AT&T or Verizon. Fitchard calculated that Sprint’s iPhone sales make up about 4 percent of Apple’s global sales last quarter.

So while customers aren’t beating down Sprint’s doors to get the iPhone and its unlimited data plan, the carrier is holding its own.

The company has been struggling a little as its makes the transition to its LTE network, coming in last in PCWorld’s test for the nation’s fastest cellular networks. The company’s WiMAx 4G network came in behind T-Mobile’s 3G network. Hesse told Cheng that he believes that if Apple decides to include 4G LTE capability in the next iPhone, Sprint will get the device at the same time as its competitors.

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