It could be the iPhone.

That’s one theory Jonathan Stephens said could explain why Sprint-Nextel lost 1.3 million customers in its third quarter, including 1.1 post-paid customers — those who, upon signing up for or renewing their services with Sprint-Nextel, paid fees to drop their plans.

“Lots of people switched to that,” Stephens, a sophomore in graphic design, said.

Stephens said he has had Sprint-Nextel service for about four years.

And he said he’s had few problems with the carrier, with the exception of reoccurring billing errors.

“There have been quite a few mess ups with our bills,” he said. “Being charged too much for things that we didn’t do or don’t have, or we upgraded and got charged if we had it upgraded.”

When Stephens’ family upgraded his plan to include unlimited text messaging, he said Sprint-Nextel charged him per text message.

Sprint-Nextel’s signal, he said, has been “alright, except for going into certain buildings” that block most cellular signal.

But the company’s loss might be attributed to more than just the iPhone, which was first released on June 29, 2007, followed by the iPhone 3G on July 11, 2007. At the end of last year’s third quarter, which would have reflected the iPhone’s arrival, Sprint-Nextel reported a profit of $64 million. The company lost $326 million — 11 cents a share — at the end of this year’s third quarter.

Emily Konides, a sophomore in political science, attributes this loss to a phone-swapping trend.

Although Sprint-Nextel played up its release of the Samsung Instinct, Konides said the phone — like everything else the company released this year — was forgetful. And people, she said, aren’t willing to swap carriers for a no-name phone.

Other wireless carriers, including AT&T, Verizon and T-Mobile, have released new versions of the BlackBerry and other PDAs, the Sidekick and the Google-accompanied G1.

Konides said she has seen people upgrading their phones each time a new, more attractive one comes out “a lot lately,” but that the action isn’t something new.

“I find it a young, more modern way of keeping up with the Joneses, where the Joneses are your peers,” she said. “It’s kind of superficial. The iPhone, I could see people doing. Not so much the Sprint thing. Companies that don’t have such big names on their newer phones, people don’t switch carriers for.”

She said although her friend purchased a new Sprint phone two weeks ago, she couldn’t remember its name.

It was the Samsung Instinct, her roommate reminded her.

Stephens said he would stay on with Sprint-Nextel for “as long as my parents pay for it.”