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T-Mobile plans to offer super-fast 5G wireless service in parts of six cities on June 28 and to begin sales of the compatible Samsung Galaxy S10 5G phone.

Customers who buy the $1,300 phone will be able to connect in areas of Atlanta, Cleveland, Dallas, Las Vegas, Los Angeles, and New York at speeds 10 to 50 times faster than with current 4G LTE phones, the carrier said. The company said it would charge the same for 5G service as with 4G LTE, in keeping with a previous promise.

T-Mobile, which is seeking to merge with rival Sprint, is furiously building a 5G network as part of an industry-wide race among major telecom companies. As the number of new wireless customers levels off, the carriers have looked for new ways to woo switchers, like rewards programs and free video and music streaming services. T-Mobile offers free Netflix, for example. But over the next few years, as coverage improves, 5G could be the big draw.

Verizon, which started selling the Galaxy S10 5G last month, is offering 5G service in parts of Chicago and Minneapolis, and has plans to add at least 30 markets by the end of the year. Last week, AT&T debuted the same phone for some businesses customers, but not for consumers. Its 5G service is online in “very limited” parts of 19 cities, and will be expanded to 30 or more cities by the end of the year.

Meanwhile, Sprint introduced its 5G service last month in Atlanta, Dallas, Houston, and Kansas City using an LG phone. It plans to add six more cities soon.

T-Mobile’s move on Tuesday represents a slight acceleration of its 5G-rollout strategy, which has lagged its main rivals. Previously, the company planned to introduce service in the second half of the year, when more 5G-capable phones are available.

T-Mobile’s timing for 5G service was based on plans to provide it by combining airwaves in high-frequency bands, like 28 GHz, with lower bands, like 600 MHz. The Samsung Galaxy S10 5G only operates in high-frequency 5G bands.

But with rivals already offering 5G service, T-Mobile decided to start slightly early with only high-frequency bands—and then add lower bands later. Therefore, T-Mobile’s 5G Samsung phone won’t be fully compatible with all bands in T-Mobile’s 5G network. The phone is still able to use slower 4G service on the lower bands.

“We look forward to bringing broader 5G to customers later this year when low-band capable devices are available,” a T-Mobile spokesman said.

The combined service would—theoretically—let customers avoid the challenges of using only high or lower frequency airwaves for 5G. So far, AT&T and Verizon are using only higher frequencies, sometimes referred to as millimeter-wave bands, while Sprint is using only a lower-frequency band.

High-frequency bands provider greater capacity for 5G data downloads, but wireless signals don’t travel as far as in lower frequency bands. The lower bands, commonly used for 4G service today, travel long distances and more easily pass through obstacles like trees and rain, but they carry less information and thus limit download speeds.

T-Mobile Is Adding 5G-Mobile Service: Here’s What You Need to Know

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