AT&T today announced that it has rolled out High Definition (HD) Voice on an all-IP, Voice Over LTE (VoLTE) network in select markets, although few will be able to use the service immediately for lack of available devices that support the feature. 

In a statement, the company said HD Voice will be available in select areas in Illinois, Indiana, Minnesota and Wisconsin, and will continue to expand on a market-by-market basis.

HD Voice will initially be available on the Samsung Galaxy S4 Mini, which according to AT&T will be “coming soon.” Additional devices are slated for market in the near future. AT&T says bringing the feature to the S4 Mini was the result of a collaboration with Samsung. 

The news comes after an earlier report from Engadget that cited a May 23 roll out for AT&T’s VoLTE service. 

AT&T’s VoLTE offering differs from the HD Voice offering recently launched by Sprint. VoLTE change means that voice calling in VoLTE markets will be moved from AT&T’s legacy circuit-switched networks and sent over the carrier’s packet-switched LTE. VoLTE promises clearer, richer call quality, and carriers are also targeting additional functionality only possible over an IP-based network. 

MetroPCS was the first U.S. carrier to launch VoLTE back in 2012. Verizon says it will launch the service later this year. 

AT&T in 2012 began its Project Velocity IP program that involves deploying thousands of small cells, which could help bolster VoLTE coverage.