After launching its HD Voice/Voice over LTE (VoLTE) service in a handful of markets in May 2014, AT&T today announced that it’s high-definition voice calling service is expanding.

AT&T HD Voice and VoLTE is now live in “select areas” of the District of Columbia, Georgia, Illinois, Indiana, Maryland, Michigan, Minnesota, Nevada, North Carolina, Ohio, Oregon, Pennsylvania, South Carolina, Texas, Utah, Virginia, Washington and Wisconsin.

While AT&T is being a bit vague about which markets now have its HD Voice support, it’s nice to see Ol’ Blue expanding its VoLTE offering to so many additional areas. It’s worth noting that in order to use HD Voice, you’ll need a compatible phone. Those include the iPhone 6, iPhone 6 Plus, HTC Desire Eye, LG G3 Vigor and Samsung Galaxy S4 mini.