SingTel, which runs the largest mobile operation in Singapore, said it would bag a world first when it launches a “full-featured” commercial VoLTE service on 31 May.

The operator – working in collaboration with Samsung and Ericsson – said the service would offer a “full suite of telephony features”, such as call waiting and call forwarding.

Dubbed 4G ClearVoice, SingTel is making the VoLTE service available to post-paid customers at no extra cost (talk-time is deducted from monthly voice minutes bundled into existing subscription plans).

And to allow LTE users to maintain voice calls when moving out of 4G coverage and moving within reach of either GSM or WCDMA circuit-switched networks, SingTel is deploying SRVCC (single radio voice call continuity) technology.

“As the first full-featured VoLTE service in the world, 4G ClearVoice is a true breakthrough in the mobile industry,” boasted Johan Buse, SingTel’s VP of consumer marketing.

Among the benefits of VoLTE, said Buse, was the ability to make voice calls at “crystal clear quality” while still maintaining a high-speed data connection. Another service advantage, he said, was the ability to connect calls in less than two seconds (up to five times faster than conventional mobile calls).

Only SingTel customers using a Samsung Galaxy Note 3, however, will be able to access 4G ClearVoice (after a  software upgrade). Galaxy Note 3 handsets sold from 31 May will come with the update installed.

Users of “other popular 4G handsets”, said SingTel, can expect to receive the update in the “coming months”.

SingTel’s announcement follows a recent spate of VoLTE activity in other parts of Asia and the US.

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 SRVCC outlined in R9.

(Huawei, HKT’s VoLTE platform provider, claimed the R10 launch in Hong Kong was a world first.)

Over in the US, AT&T said last week it would launch its first commercial VoLTE service, in selected markets, on 23 May.