Nepal Telecom had been testing VoLTE service when it started the expansion of 4G to more areas. Now that Ntc 4G coverage is now available in all 77 districts and testing is successful, they have launched the VoLTE service on the occasion of World Telecommunication and Information Society Day (May 17, 2021, that is Jestha 3, 2078). VoLTE provides HD voice and video over the 4G network.
As 4G is a data-only technology, a telco needs to have either extra features to support voice over 4G or use the existing legacy networks like 2G, 3G while being on 4G. The extra feature solution to provide Voice service over 4G LTE is VoLTE (Voice over LTE). It is similar to Voice over IP, which means the voice passes through the data network for the voice service. VoLTE is also one of the most demanded services from Nepali Telecom operators, find other demands by people.
VoLTE works in the same way as the OTT applications like Viber, Skype, messenger but you can call using your own number through 4G. In this technology/service, you can just make a call in the same way as before in 2G and 3G. As known, the call charge of VoLTE will be as per the cost per minute (or pulse rate) as the traditional voice service.
Source: https://www.nepalitelecom.com/nepal-telecom-ntc-volte