Northrop Grumman experimental FCC license at the Nevada Test Site

apps.fcc.gov...

Purpose Of Operation: Demonstration of deployable 4G mobile communication solutions at the Nevada Test Range to the U.S. military.

This may be the for the military smartphone that Northrop is developing. There is a GSM 750 as well (similar frequencies), but I don't know if this device uses that standard.

A bit more information here:
transition.fcc.gov...
and
www.psst.org...

It may be they decided to expand the market to DoD use, but basically they are setting up what amounts to a cell phone network (LTE) for public safety. Motorola was running similar tests at Holoman AFB.

If life were a dry lake bed, even the iphone 4 would work there, death grip and all. [No obstructions on the dry lake] So what this testing actually proves in terms of normal operation is dubious, but perhaps they want to test the system in the presence of jamming, since that would be needed on the battlefield.