U.S. carrier T-Mobile has announced that HD Voice is now available on its network nationwide. To experience HD Voice, both parties on the call must use capable T-Mobile 4G smartphones such as the HTC One S, Nokia Astound and Samsung Galaxy S III on T-Mobile’s HD Voice-enabled nationwide network.

Operator is also making continued coverage improvements and launching an advanced LTE network that will reach 100 million people by mid-year and 200 million people by end of year.

In addition, at 2013 International Consumer Electronics Show (CES), T-Mobile also announced that its popular Unlimited Nationwide 4G Data plan will be available with no annual contract starting tomorrow. The new plan will be available with no annual contract for $70 per month.

T-Mobile’s $4 billion plan to advance its competitive 4G network continues, improving signal strength and in-building coverage and re-tuning its airwaves to launch 4G service in an additional frequency, 1900 MHz, providing a 4G experience to a broader range of consumer devices, including the iPhone. 

Today T-Mobile added new metro areas, including Denver, Los Angeles, San Diego and Virginia Beach, Va. These network enhancements now reach 126 million people in 46 metro areas including major cities such as Atlanta, Boston, Chicago, Dallas, Detroit, Houston, Las Vegas, Miami, Minneapolis, New York, Philadelphia, Phoenix, San Francisco, Seattle and Washington, D.C. According to T-Mobile, its nationwide 4G network now covers 229 metro areas reaching well over 220 million people.