AT&T announced it will launch its first commercial VoLTE service, in selected markets, on 23 May. With an eye on the consumer, however, AT&T emphasised it would use VoLTE to debut a HD voice service capable of giving “crystal clear” conversations.

HD voice will initially be available on the Samsung Galaxy S4 mini. More HD voice-enabled devices, said AT&T, are on their way.

The first markets where the service is to be made available are Illinois, Indiana, Minnesota and Wisconsin.

AT&T’s announcement follows a spate of VoLTE activity this week.

NTT Docomo in Japan said it was targeting a commercial VoLTE service by the end of June, while HKT in Hong Kong launched VoLTE using eSRVCC (enhanced single radio voice call continuity).

Stipulated in 3GPP Release 10, enhanced SRVCC enables call handover between LTE and 3G networks at lower latency than plain SRVCC outlined in R9. Huawei, HKT’s VoLTE platform provider, claimed the R10 launch in Hong Kong was a world first.

AT&T did not name its VoLTE platform suppliers, or disclose whether or not SRVCC technology is used.

Verizon Wireless, the largest mobile operator in the US, has still to launch VoLTE.