The coming launch of Samsung's "pure Google" Galaxy Nexus smartphone on Sprint Nextel's network this week helps the No. 3 carrier (by subscriber base) catch up with its more popular rivals in the device lineup.

But in an unusual move, Sprint is releasing the phone, which is compatible with 4G long-term evolution data networks, before Sprint's LTE network launches, which won't happen until midyear. The Nexus hits Sprint stores Sunday, with those who pre-order early enough eligible to get it two days earlier.

Also on April 22, Sprint will launch the 4G capable Viper by LG, for $99 with a two-year contract.

3G for Now

For now, the LTE-capable phones will work with Sprint's 3G network, and not use the carrier's high-speed WiMAX data network, which it also calls 4G.

Handset expert Peter Han of Current Analysis told us that Sprint's move is unique in that Sprint has no publicly accessible LTE network at the moment, but he noted that both AT&T and Verizon Wireless initially launched LTE on a limited scale while offering LTE-capable smartphones nationwide. (Verizon initially offered LTE only for computer modem users before adding smartphones several months later.)

For Sprint, it makes little sense to hold back on the Nexus while it is already being sold by rival Verizon Wireless (which has the largest LTE network, but still has some gaps.)

"Sprint's LTE network is initially launching in a couple of metros, so the majority of its consumers will not have access to LTE at launch [anyway]," Han said.

Adding more value to the Sprint version of the Nexus, its near-field communication chip will be active, allowing users to use Google Wallet for payments with their phones. As a promotion Google is offering early adopters -- those who open a Wallet account within a week of activation -- a $10 credit, with an addition $40 in the first three weeks.

The Nexus packs a 1.2-GHz dual-core processor, a 4.65-inch Super AMOLED contoured display and 5-megapixels in the rear and 1.3 megapixel camera up front. The Nexus, created jointly by Samsung and Google, is the first to ship with Android 4.0 (Ice Cream Sandwich).

With Apple's iPhone, which came to Sprint in October, the Nexus will be a second top-shelf device for the carrier and with a price that undercuts Verizon Wireless by $100, at $199 with a two-year contract.

"Galaxy Nexus is a beautifully designed smartphone that combines the Pure Google experience with the speed of Sprint's upcoming 4G LTE network," said Sprint's Fared Adib, vice president of product development, in a statement. "It represents the cutting-edge features and applications that customers expect and pairs perfectly with Sprint's unlimited data plans to let our customers enjoy their wireless experience without worrying about overage charges or throttling."

Hold the Base

Han said the Nexus stands out not only because of the phone's features but because of the timing.

"There has not been a significant smartphone at Sprint this year, mostly due to Sprint discontinuing WiMAX smartphone launches and readying its LTE network," Han said. "While the Samsung Galaxy Nexus is currently the top Android smartphone, early adopters have been able to pick it up at Verizon Wireless since December."

Han added that a slow LTE rollout while rivals Verizon and AT&T are already selling a range of LTE devices puts pressure on Sprint.

"AT&T and Verizon Wireless already have a wide variety of LTE smartphones, and it will take a while before Sprint catches up," he said. "Sprint's Galaxy Nexus along with the HTC EVO 4G LTE are to appease Sprint's current customer base, as most consumers [care about] carrier first and device second."

Sprint LTE will debut in Atlanta, Dallas, Houston and San Antonio, but The Wall Street Journal recently reported that the network is active for testing in some small towns.