T-Mobile turned on its 5G network nationally and in Houston Monday, but you'll have to wait until later in the week to get your hands on a smartphone that will let you use it.

The carrier originally said its 5G network, which uses a lower-frequency spectrum than competitors AT&T and Verizon, would be lit up Friday. Instead, that’s when a pair of 5G-capable handsets that work with it will become available for sale.

Mark McDiarmid, T-Mobile’s senior vice president of Radio Network Engineering & Development, said the network covers 1 million square miles and 200 million people. Based on an early map of the network, it includes most of the Greater Houston area.

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“This is the first nationwide 5G network,” McDiarmid said.

With the launch, there are now three commercially available 5G mobile data networks in Houston. Sprint — which is planning a merger with T-Mobile — launched its network earlier in the year. Verizon turned on its network locally last month. AT&T has a 5G network operating in Houston, but is available by invitation only to select businesses.

Sprint’s network covers the central part of Houston and spreads mostly north and west. Verizon’s mobile 5G network has the spottiest coverage, available in only a handful of locations around the city.

Both Verizon and AT&T are using high-frequency spectrum known as millimeter wave, or mmWave. High-frequency radio waves have difficulty penetrating barriers, including buildings and even dense foliage. Verizon’s UltraWideband network, as its 5G mobile service is branded, only works outside, and many of its active locations around Houston are areas where people gather.

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T-Mobile is using the 600-megahertz spectrum, which can pass through buildings. It won’t be as fast as Verizon’s and AT&T’s flavors of 5G, but still faster than 4G. T-Mobile is also using part of the 600-Mhz spectrum for its LTE-based data service, which is one reason it’s able to provide such wide 5G coverage, which includes many rural areas.

“On average T-Mobile customers using our 5G network will see about a 20 percent increase in speeds,” McDiarmid said, adding nationally the average speed seen by the carrier’s current 4G customers on LTE is around 35 megabits a second.

By contrast, a demonstration of Verizon’s 5G service in Houston last month showed speeds well over 1.5 gigabits a second — but only outdoors and within line-of-sight of a transmitter.

T-Mobile will start selling two Android phones Friday that work on its network — Samsung’s Note 10+ 5G, which has a list price of $1,300, and the OnePlus 7T Pro 5G McLaren, which lists at $900. A variety of deals cut down on those costs, and the OnePlus phone is available free for new customers to sign up and trade in their existing phones.

T-Mobile will not charge extra for 5G service, Diarmid said. Customers with 5G-capable devices on its network will pay the same price as 4G users. The company has been under pressure from regulators eyeing its merger with Sprint to keep its prices low.

5G is the next-generation of wireless data standards, the expected successor to the current 4G LTE. Proponents say it will usher in a new wave of services and applications with faster speeds and less lag.

T-Mobile is using 5G’s benefits as part of the push for its merger with Sprint, which has passed muster with federal regulators but still faces a lawsuit from a coalition of state attorneys general. Texas Attorney General Ken Paxton settled last week with T-Mobile and withdrew from the suit. T-Mobile wants to combine its 5G assets with those of Sprint to better compete with AT&T and Verizon.

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