VoLTE, sometimes also known as HD Voice, is a technology that brings voice calls over a 4G LTE network. The higher bandwidth of 4G LTE networks make it ideal to transmit higher fidelity voice calls than over the 2G and 3G networks. Along with that, VoLTE also brings with it noise cancellation capability. Both features are dependent on the mobile devices used for voice calls.
Another advantage of VoLTE is it allows customers to simultaneously surf the web, download or stream content from the internet at 4G LTE speeds while engaged on a voice call. Currently, the need to use 3G or 2G infrastructure to connect voice calls means internet activity will drop to slower speeds.
Digi already offers HD Voice (high definition voice quality) via its 3G network along with two other Malaysia operators. However Digi is currently the only Telco that has announced its intention to launch VoLTE.
Digi said the VoLTE test implementation (internal) in Digi is already underway and subscribers can expect to enjoy the improved call experience on compatible 4G LTE smartphones sometime in 2016.
http://www.malaysianwireless.com/2015/10/digi-voice-over-lte-volte-testing-zte/
