T-Mobile US said it would deploy fifth-generation wireless technology across the US by 2020, pitting itself against bigger rivals already laying the groundwork for their own network upgrades.
The pledge came as AT&T, Straight Path Communications and Verizon Communications are pouring billions of dollars into wireless airwave licences that might support 5G.
AT&T and Verizon have also tested 5G ideas on equipment used to beam information into homes.
T-Mobile has forked out $8 billion to acquire more conventional low-band spectrum that travels farther.
