T-Mobile said Thursday that its new 600MHz LTE sites will be ready for 5G -- when that technology arrives -- as the first smartphone compatible with the 600MHz frequency on LTE is unveiled.

T-Mobile US Inc. started to switch on the 600MHz 4G LTE sites earlier this month, using equipment from Ericsson AB (Nasdaq: ERIC). The operator now has sites live in Wyoming and Scarborough, Maine, which it says will be 5G-ready.

"When it's time to launch 5G technology for consumers, the Un-carrier can upgrade this already-deployed 5G-ready equipment via software update, effectively turning on 5G on 600 MHz with the flip of a switch without having to touch towers twice," the operator says in a statement.

T-Mobile expects to launch 5G on 600MHz in 2019. (See T-Mobile on 5G: Starting With 600MHz, Looking at mmWave Future.)

T-Mobile expects to have 1.2 million square miles of rural America covered with 600MHz by the end of the year. This will include parts of Kansas, Maine, North Dakota, Oregon, Pennsylvania, Texas, Washington and other states later this year.

This raises the intriguing prospect that some of T-Mobile's first 5G launches could be in rural America rather than big cities.

Of course, an advanced 4G LTE -- or even 5G-ready network -- means nothing if consumers can't buy compatible devices. LG Electronics Inc. (London: LGLD; Korea: 6657.KS) today unveiled the V30 -- the first smartphone available globally to support 600MHz -- T-Mobile says it will start selling it in the fall. The V-models from LG are known as a series of state-of-the-art Android devices for audio and video recording.

— Dan Jones, Mobile Editor, Light Reading