Voice over LTE is a mature technology that allows for higher-quality voice calls over the 4G LTE protocol, rather than using the standard cellular voice system. It’s been standard issue on high-end phones on most American networks for years now, but then again, Sprint isn’t most networks.

The company has finally started a soft launch of VoLTE, with a couple of Samsung devices and 15 regions getting the feature right now. More cities and phones are being promised in the coming weeks, but it’s unclear whether it will be completely rolled out before T-Mobile formally gobbles up Sprint.

At launch, the Samsung Galaxy S8, S8+, and S8 Active have VoLTE enabled. You’ll need to go into your Voice Networks setting to enable it; if you’re on a compatible device in an included market and the option still doesn’t become available, a restart may help.

The included markets are:

Atlanta-Athens

Chicago

Dallas-Ft. Worth

Houston

Indianapolis

Kansas

Missouri

New York City

Oregon-West Washington

Philadelphia

Pittsburgh

San Francisco Bay

South Bay

Southern Jersey

Washington, DC

Sprint has been filling the gap with a proprietary service it calls Calling PLUS. That enabled calls over Wi-Fi as well as over LTE, although the company always pushed the biggest benefit as being able to use data whilst also on a voice call. Calling PLUS is being replaced by VoLTE, and will be disabled progressively as VoLTE rolls out in new markets.