South Korea's LG U+ and Japan's KDDI have launched what they are billing as the world's first commercial international VoLTE roaming service.
Subscribers to both operators will be able to make high-definition voice and video calls over the other's network while travelling overseas, Korea Herald reported.
The VoLTE service allows for real-time switching between HD voice and video calls, as well as the ability to share multimedia content while making voice calls.
The service is currently only available over a single handset – the LG Electronics G Flex 2 smartphone. LG U+ plans to introduce more smartphones, and introduce the service for more countries, in the near future.
LG U+ launched LTE services in 2011, and achieved nationwide coverage the following year.
Interest in VoLTE roaming is increasing as VoLTE adoption improves. In February, Japan's NTT DoCoMo, South Korea's KT and the US-based Verizon Wireless completed feasibility tests of VoLTE roaming, and DoCoMo revealed plans to commercialize VoLTE roaming by the end of the year.
China Mobile meanwhile has VoLTE roaming deals in place with companies including KT and the Netherlands' KPN.