As per the article below, Microsoft wants to close the rural broadband gap with TV white spaces. Unused TV white spaces operating in the 600 MHz frequency range will be repurposed for Microsoft's projects
https://www.theverge.com/2017/7/11/15953310/microsoft-rural-airband-broadband-strategy
https://www.theverge.com/2017/7/11/15953310/microsoft-rural-airband-broadband-strategy