Now that Sprint Corp.'s LTE network has grown to include 150 markets, at least one of its many mobile virtual network operators (MVNOs) is ready to make the leap from one flavor of 4G to the other.

FreedomPop said Tuesday its customers will now have the option of migrating from WiMax to Sprint's small but growing LTE network. FreedomPop announced the FreedomSpot 5580 mobile hotspot that runs on Sprint's LTE network in the 150 markets it where it has the 4G network up and running in the U.S. The $149 device comes with 500MB of data free and includes 3G fallback.

FreedomPop tells GigaOm it has added 100,000 customers in its first year of service, 55 percent of which don't pay for access. Those customers use its FreedomPop WiMax hotspot where Sprint has the 4G network. Those that own the WiMax hotspot will be able to pay the difference, $60, to upgrade to the LTE version. (See Summer of LTE: 4G Blooms in UK & US.)

FreedomPop's business model is to offer the initial 500MB of free data, with the hope that customers will tack on more megabytes either through sharing with a social network, redeeming offers and promotions or paying for service. The remaining 45 percent of FreedomPop's customers pay for monthly service, either in whole or in conjunction with free offers. The MVNO, which also recently attracted $5 million in funding to support its "freemium" business model, plans to offer refurbished $99 Android phones sometime this summer. (See FreedomPop Grabs $5M to Support Android.)

It was beaten to the punch Tuesday by a fellow Sprint MVNO, TextNow. The virtual operator said it will be selling refurbished Samsung Galaxy S IIs and Galaxy Nexuses equipped with its voice and text app on board and traditional telephony turned off. All communications, text and voice, goes over Sprint's 3G data network. Its plans start at $18.99 for 50MB of data and 750 roll-over minutes.

— Sarah Reedy, Senior Editor, Light Reading