Sprint, America's third-largest mobile carrier, just revealed some of its first 4G LTE networks, which extend to areas such as Tennessee, Illinois and New York. The mobile service carrier's efforts to build a robust 4G network could be in anticipation of Apple's next-generation smartphone, the iPhone 5.

When the iPhone 4S made its debut on Sprint's network in the fall, the company held high hopes for the Apple device and its upcoming 4G network. However some analysts wondered whether or not Sprint's new 4G network could support the release of the highly-anticipated iPhone 5, according to the iPhone 5 News Blog.

We believe an LTE iPhone will likely be badly disadvantaged on Sprint's network, partially impairing sales at a time when Sprint is subject to a punishing take-or-pay deal with Apple, Bernstein Research analyst Craig Moffett told Forbes in March.

Moffett went on to say that Sprint may not have a concrete enough 4G spectrum to launch a cutthroat smartphone, and could possibly falter in comparison with other carriers.

The problem is 4G, he said. Sprint doesn't have enough free-and-clear spectrum on which to launch a competitive LTE network, and it doesn't have the money to clear spectrum that's already in use. We expect Sprint's competitiveness to begin to blackslide when LTE becomes the nation's de facto standard.

However, despite these reservations, the network is continuing to push forward an expansion of its LTE. A report from Techno Buffalo reveals a leaked document indicating that the company is aggressively rolling out its 4G network across top U.S. mobile markets, perhaps in a bid to prepare itself for a massive 4G iPhone 5 release that could be coming sooner rather than later, writes Michael Nace of the iPhone 5 News Blog.

According to the tech news website, Sprint is much further along that critics would expect, with the internal document suggesting that the network campaign is underway in Akron, Chicago, Fort Worth, Nashville, New York, Rialto and Stockton.

Earlier in April the company also revealed that 4G LTE service will be coming to six lager markets in June, which is a predicted month for the iPhone 5 launch. The service is already up and running in Kankakee, Ill. according to The Wall Street Journal. A Sprint spokeswoman also told the publication that the carrier has 4G LTE towers functioning in several other markets, but wouldn't reveal where.

I find it interesting that they've launched the LTE product nationwide without the network more in place George Colonel, an independent Sprint dealer with four stores near the Cincinnati area, told WSJ. But unfortunately, sometimes that's how it's done.

Sprint is implementing a strategy to release its LTE-enabled devices before the network is finalized. The LG Viper and Galaxy Nexus are expected to launch on April 22nd and will both feature 4G LTE. This is an effort to keep up with rivals such as Verizon Wireless in being able to offer what is becoming the industry standard.

Sprint's LTE movement is yet another piece of evidence some iPhone enthusiasts can chalk up to a June release date, but until Apple makes the big announcement there is no way to be sure. In addition to LTE service, the next generation gadget is said to feature OLED display, crack-resistant glass and the iWallet, which is a digital system that allows users to have complete control over financial accounts via their iPhone.