Korea, which presented the world's first VoLTE service in 2012, is now getting ready to present the world's first inter-carrier VoLTE service in November. The Ministry of Science, ICT, and Future Planning (MSIP) announced on the 17th that the Korean big 3 mobile carriers would participate in a trial VoLTE service at the end of June, and gradually expand it until the service is fully launched in November.
 
VoLTE uses packet (data) method in processing voice calls. And this gives excellent call connection time, only 0.25~2.5 seconds. This is nearly 20 times faster than 2G or 3G which uses circuit (voice) method instead.
 
Unlike the conventional circuit (voice) method that uses only 200~3400 Hz, VoLTE supports up to 50~7000 Hz, allowing for high quality sound, almost as good as original sound. Also for video calls, VoLTE provides much higher definition than 3G, more than 8 times better, making it possible to transmit pictures or video clips even during calls. If all voice data travel over LTE, multifarious multi-media services can be offered faster, and more convergence services like 'real-time mobile translation system', 'mobile medical consultation system', etc., will become available.

Conventional VoLTE so far has been available only for calls between subscribers of the same mobile carrier within the carrier's network, and not between subscribers of different carriers. But, now the new inter-carrier VoLTE will give users of the 3 different mobile carriers opportunities to enjoy high-quality voice service and other various features across the carriers' networks. Any LTE service subscribers with a VoLTE-enabled device (released after July 2012) can use the service.

Below is the commercialization schedule of the inter-carrier VoLTE service. After a trial service period in June and July, the service will also become available for general users in August, and then for all subscribers who have a VoLTE-enabled device in November. MSIP, in cooperation with the big 3, is planning to conduct additional quality tests against all 174 VoLTE-enabled devices currently available in the nation.