Microsoft is seeking FCC authorization to test "a private wireless mobile network" using spectrum currently owned by all three of the nation's big 5G operators: T-Mobile, AT&T and Verizon.

According to the company's filings with the FCC, the tests are scattered across Microsoft corporate campus locations in Bellevue and Redmond, Washington. The company did not provide any further details about the tests, and requested that the FCC keep some of the documents related to the tests confidential. Microsoft declined to answer questions about the tests from Light Reading.

Brian Goemmer, the founder of spectrum-tracking company AllNet Insights & Analytics, identified the 24GHz and 37GHz spectrum licenses involved in the tests as belonging to, variously, AT&T, Verizon and T-Mobile.

Microsoft's tests of a private wireless mobile network in millimeter wave (mmWave) spectrum bands owned by the nation's big wireless network operators comes just months after the company closed two major acquisitions in the mobile industry. Microsoft first acquired Affirmed Networks for a rumored $1.35 billion and then weeks later it acquired Metaswitch Networks. Both companies provide deep telecom networking services to network operators around the world.

Microsoft has also been clear about its private wireless networking ambitions. For example, the company has highlighted its work with Attabotics, a Canadian maker of robotic supply chain solutions that uses Microsoft's edge computing and IoT solutions on a private LTE network relying on equipment from Ericsson and 2100MHz spectrum from Canadian wireless network operator Rogers.

Thus, Microsoft's mmWave tests could give it additional insight into private wireless networks in higher spectrum bands. AT&T, T-Mobile and Verizon are all variously using mmWave spectrum for 5G operations.

— Mike Dano, Editorial Director, 5G & Mobile Strategies, Light Reading | @mikeddano