T-Mobile (NASDAQ: TMUS) announced today it achieved another 5G U.S. first in a test that leveraged 5G standalone millimeter wave (mmWave) on its production network. Working with Ericsson and Qualcomm Technologies, Inc., the Un-carrier aggregated eight channels of mmWave spectrum to reach download speeds topping 4.3 Gbps without relying on low-band or mid-band spectrum to anchor the connection. T-Mobile also aggregated four channels of mmWave spectrum on the uplink, reaching speeds above 420 Mbps. “We’ve always said we’ll use millimeter wave where it makes sense, and this test allows us to see …