T-Mobile has started 600 MHz (Band 71) Extended Range LTE in 1,254 cities and towns in 36 states in the US.

The deployment of 600 MHz LTE is expanding network coverage and capacity, particularly in rural areas, and lays the foundation for nationwide 5G in 2020 with 5G-ready equipment, Un-carrier said.

T-Mobile said it aims to deploy up to 50 MHz of 600 MHz spectrum in the Puerto Rico island.

“With 600 MHz now live across Puerto Rico, we’re helping the island position itself as a future tech leader as it continues to rebuild after last year’s hurricanes,” Neville Ray, chief technology officer of T-Mobile, said.

T-Mobile US in a statement issued on Monday said that the Extended Range LTE signals travel twice as far from the tower and are four times better in buildings than mid-band LTE, providing increased coverage and capacity.

The Un-carrier has already deployed Extended Range LTE to more than 80 percent of Americans with 700 MHz (Band 12), and rapidly began deploying it with 600 MHz (Band 71) last year to expand coverage and capacity.

T-Mobile in April 2017 made its largest network investment, tripling its low-band spectrum holdings by purchasing spectrum during US government’s 600 MHz auction. Those licenses cover 100 percent of the US, including Puerto Rico.

T-Mobile offers 14 600 MHz-capable smartphones across all price points in the US. The Un-carrier has also enabled carrier aggregation for 600 MHz Extended Range LTE and mid-band LTE.