Sprint's data-hungry customers can breathe a sigh of relief. The carrier's commitment to unlimited data plans remains unwaivering--at least for now.

So said Sprint Chief Technology Officer Stephen Bye when addressing attendees of GigaOm's Mobilize conference in San Francisco today.

While main competitors Verizon and AT&T are slashing their unlimited plans, Sprint sees it as a differentiator.

"There's clearly a cost to support unlimited," Bye admitted, adding that not every unlimited subscriber is as high a data user as his or her neighbor. At the same time, Bye emphasized the simplicity of supporting an unlimited data plan, citing the hidden cost for customer care and support related to tiered data plans.

Still, that cost would hardly displace the larger fee of maintaining and deploying a data network, especially a 4G network at that.

Despite an upbeat assurance that Sprint is in good competitive shape, Bye acknowledged the market pressure of maintaining an unlimited plan. "Is there pressure? Yeah," Bye said. "There's a challenge for all engineers to work on how we get the cost structure down."

Modernizing Sprint's network is the first step, especially phasing out its iDEN network and reallocating that network's budget to pay for current users' data habit. As for the rest, Sprint's partnership with LTE wholesaler LightSquared gives Sprint a de facto road map for deploying its own 4G LTE network to compete with Verizon and AT&T (Sprint currently uses Clearwire's WiMax.)

Sprint may be preparing to woo investors and analysts with a forthcoming statement on their 4G strategy, according to Bye, but that doesn't solve the problem of luring new customers and keeping the old, especially when they're also slashing perks for long-time loyalty.

Despite all that, Bye didn't drift too far from the message that Sprint wants to give people what they care about: free phones, simple plans, and unlimited data.

However what Sprint wants to give may not be what people eventually get. Signs and reports point to Sprint landing the iPhone soon, and if it does, it's a strong bet that the No. 3 carrier won't have the capacity to sustain unrestricted data for long, despite Sprint's assurance that it would.