https://www.cnet.com/news/t-mobile-hits-5g-milestone-using-600-mhz-spectrum/

T-Mobile says the test is a milestone in the evolution of 5G because it demonstrates how multiple types of wireless spectrum -- low-band, mid-band and millimeter wave -- can be used to deliver 5G services. Up to this point, T-Mobile's rivals, AT&T and Verizon, have only demonstrated testing of 5G services using very high frequency millimeter wavelength spectrum. T-Mobile says it's important to show the technology can work across a range of spectrum, which will ensure the service can be deployed nationwide and accessed indoors. 

"While the other guys focus on 5G millimeter wave on a handful of blocks in a handful of cities, we're building 5G for everyone, everyone," T-Mobile CEO John Legere said in a statement. "And together with Sprint, we'll add much-needed spectrum depth, creating a truly transformative 5G network."