Leaving the lab behind, Sprint has completed the first 5G data call using 2.5 GHz spectrum and Massive MIMO on the carrier’s commercial network in San Diego.

The field test took place this week with partners Qualcomm and Nokia. Sprint used Nokia’s dual-mode AirScale Massive MIMO radio, and a smartphone form-factor test device from Qualcomm powered by the Snapdragon X50 5G modem and antenna modules.

Sprint said the trial—which included Skype audio and video calls, sending and receiving Instant Messages, and streaming YouTube videos—showed a “seamless transition of connectivity” between the carrier’s 4G LTE-A and 5G network.

“This is a big step forward – Sprint 5G is now out of the lab and in the field as we prepare for our commercial launch in the first half of this year,” said Sprint CTO Dr. John Saw in a statement.

Earlier this week, Sprint said it would introduce a 5G smartphone from Samsung this summer with dual-mode connectivity supporting the carrier’s 2.5 GHz spectrum for both 5G and LTE. Sprint has also promised to deliver the first 5G smartphone in the U.S. from LG. Samsung 5G smartphones are also expected from Verizon and AT&T.

Virtually all 5G mobile devices launched in 2019 are expected to be powered by Qualcomm products, with the chipmaker announcing this week that more than 30 commercial mobile devices will be powered by the company’s chipsets and RF front end this year.

Sprint plans to first launch its mobile 5G service in the downtown area of nine cities, including Atlanta, Chicago, Dallas, Houston, Kansas City, Los Angeles, New York City, Phoenix and Washington, D.C.

“By using 2.5 GHz for 5G, existing sites nationwide can be re-used, with indoor coverage as well,” said Mike Murphy, Nokia’s CTO for North America. “This first standards-based call is thus a critical step towards Sprint’s offering of a 5G service to its customers.”

While Sprint is leaning on its large 2.5 GHz holdings for 5G, AT&T and Verizon are both initially using millimeter wave spectrum for their respective mobile 5G offerings. After launching a fixed wireless 5G home broadband offering in October, Verizon said its mobile 5G would be available in early 2019, but the operator has yet to announce a launch date.

AT&T, meanwhile, had a limited roll out of its mobile 5G service at the end of 2018 – but was only made available to certain customers on a free trial basis in parts of select cities.

T-Mobile, which is still working toward approval for its proposed merger with Sprint, has committed to delivering a nationwide 5G network by 2020.

AT&T recently riled up all three of its competitors (as well as consumers) by updating connectivity icons on certain smartphones to display a “5GE” logo when users connect to certain parts of the carrier’s 4G LTE network. Even though those portions of AT&T’s network were upgraded to boost speeds, there has been outcry over the use of ‘5G’ to describe it.

Sprint’s Saw said in a statement to Engadget that “AT&T is blatantly misleading consumers – 5GE is not real 5G.”