The number three wireless carrier is working hard to catch up to its rivals in offering high-speed, long-term evolution (LTE) data transfer for its devices, and service is already up and running in some small markets.

But analysts say it will be some time before LTE becomes standard for high-speed data on smartphones.

"LTE is going to take some time to fully get into customer use," William Ho of Current Analysis told us. "Carriers are using handsets as the means to transition users to the more efficient LTE network."

Small Town Testing

Large-scale LTE service will roll out for Sprint Nextel customers around mid-year, with service in Atlanta, Dallas, Houston and San Antonio, Baltimore and Kansas City, ultimately covering 120 million people by year's end. But service is already active in some very small markets.

The Wall Street Journal reported that Kanakee, Illinois, a town of 27,537, located 60 miles from Chicago, is one such market where Sprint is ironing out the LTE kinks.

Sprint is no doubt feeling the heat to have the network ready in time for the next iPhone release from Apple, expected this summer. The new version is widely believed to be LTE-capable since the latest iPad tablet, released last month, is also LTE-equipped.

Sprint is also promising enhanced 3G service to prevent speed degradation when customers leave 4G-enabled areas with LTE devices.

"Sprint is investing in its CDMA network," said Bob Azzi, Sprint senior vice president for Network in a recent statement. "We continue to deploy multi-mode base stations across Sprint's nationwide cell sites and are expecting improvements in voice quality, signal density and data speeds."

Sprint already uses the WiMax standard, which it also calls 4G, for some devices. The new phones that will be LTE-enabled include Samsung's Galaxy Nexus and LG's Viper. The carrier will also sell a 4G Sierra Wireless Tri-Network Hotspot, which works for 3G, WiMAX and LTE.

Ho of Current Analysis said LTE makes sense for carriers because it is cheaper to operate (after the initial investment) than a 3G network. However, "Unless users transition to LTE devices, carriers still will have to operate 2G/3G networks. Those networks will remain in place for some time unless carriers are more aggressive with build-out and the FCC allows for more spectrum."

Voice Over Data

One factor that may drive adoption of LTE smartphones is the emerging availability of voice over LTE or VoLTE, allowing users to place calls through their data plans and save minutes, much the way voice over Internet protocol does with computers, cutting down on plan minutes (a particular boon for those with unlimited data plans).

"[This] represents the promise of more efficient voice for the carriers because calls will ride on the data channels rather than dedicated channels," said Ho.

Another factor that stands to drive LTE, said Michael Morgan of ABI Research, is an LTE iPhone available via Sprint, Verizon and AT&T.

"The iPad 3 is a great indicator that they now have [LTE] on a mobile device so they can work out the bugs" for the iPhone, he said. "Fifty percent of wireless consumers now have smartphones, and I wouldn't be surprised if, in the next four years that went up to 75 percent, with the remainder being people who will probably never get one because they don't get it."

In the next few years, Morgan added, other carriers are likely to follow Verizon's example and release only LTE-equipped smartphones as new offerings.

However, it would likely be at least a decade before carriers can start ditching their 2G and 3G networks. "They need to have a safety fallback for regions where it isn't worth getting LTE out to," said Morgan.