US operator Sprint has announced nationwide availability of HD Voice services, which it says are currently supported on 28 smartphones for its post-paid subscribers and 33 handsets for pre-paid Sprint users, while it estimates that approximately 16 million of its customers are already using an HD Voice enabled device, Telegeography.com reports.

Sprint also announced that it has extended its 4G LTE mobile broadband footprint to 28 additional markets nationwide, raising the number of cities covered to 471, up from 402 markets in March. The new markets include Seattle, Cleveland and San Jose, and the LTE network now covers over 225 million people, with Sprint aiming to increase this figure to 250 million in the short term.

In addition, Sprint has expanded its ‘Sprint Spark’ branded LTE-Advanced (LTE-A) network coverage (with average data speeds of 6Mbps-15Mbps and peak speeds of 50Mbps-60Mbps) to three additional markets — St. Louis, Winston-Salem and Greensboro, NC, taking the total footprint to 27 cities, up from 18 in March. It aims to reach 100 million people with LTE-A services by the end of 2014 and 100 cities in the next two-three years.