Sprint has completed a 5G milestone in its effort to roll out a mobile 5G network.

Sprint today confirmed that it completed an over the air 5G data transmission using 2.5GHz and Massive MIMO on its live commercial network. The test was conducted in San Diego using global standards with Sprint's 2.5GHz spectrum, a Nokia dual-mode AirScale Massive MIMO radio, and a Qualcomm smartphone test device with a Snapdragon X50 5G modem.

In the test, Sprint showed off a transition between its 4G LTE Advanced coverage and its 5G network while streaming YouTube videos, conducting Skype audio and video calls, and sending and receiving instant messages.

Sprint has said that it's planning to launch its mobile 5G network in the first half of 2019. It'll be available in nine cities to start: Atlanta, Chicago, Dallas, Houston, Kansas City, Los Angeles, New York City, Phoenix, and Washington D.C. The rollout will include "mobile 5G footprints" in the downtown metros of these cities.

When it comes to 5G smartphones, Sprint recently confirmed that it will sell a 5G Samsung smartphone this summer.