The US mobile operator T-Mobile is supplying VoLTE to 15 markets, and now covers more than 107 million people, Lteworld.org reports, noting that the company expects to deliver VoLTE across the country by the end of 2014.

It is now offering VoLTE on a fourth device – the Samsung Galaxy S 5 – starting Thursday. The markets are: Atlanta, Ga; Austin, Dallas, and Houston, Texas; Boston, Mass; Chicago, Ill; Long Island and New York, NY; Los Angeles and San Francisco, Ca; Minneapolis, Minn; New Jersey; Philadelphia, Pa; Seattle, WA; and Washington, DC.

In addition, T-Mobile expects to have its LTE for 230 million people by the end of this month and is expanding the list of cities and markets with Wideband LTE. It is providing at least 15+15-MHz in 16 markets across the country, Atlanta, Ga; Birmingham and Mobile, Ala; Columbus, Ohio; Dallas and Houston, Texas; Detroit, Mi; Honolulu, Hawaii;; Jacksonville, Orlando, and Tampa, FL; Los Angeles, Ca; Minneapolis, Minn; Portland, Ore; Seattle, Wash; and upstate NY.