The VoLTE service will be deployed through a system called IMS (IP Multimedia Subsystem). At present, Viettel’s technical team has completed the installation, configuration and integration phase of this system and is currently working with terminal vendors such as Apple, Samsung,… to configure the parameters on the phone lines allowing the customer to be able to use VoLTE. It is expected that VoLTE will be officially launched in December this year in Vietnam.

With VoLTE, customers can make calls on 4G networks with without having to switch to 2G or 3G networks.

Currently, when customers using 4G service make a call, the system will automatically switch the calls to 3G or 2G. This solution called CS Fallback (CSFB) and it is considered a quick and simple solution that is suitable for 4G LTE deployments with existing 2G and 3G network infrastructure.

Until now, Viettel has also implemented voice features on 4G networks by this solution. However, the limitations of these calls are that the call quality is normal, it does not help customers experience the different of 4G LTE technologies, and that the call setup process is also slower, consuming resources on 2G and 3G networks.

Compared with CS Fallback solution, VoLTE service is a promising experience bringing many breakthroughs to Viettel's 4G customers because it really increases the customer's satisfaction in terms of call setup time and voice quality without incurring any additional fees from the customer.

More specifically, the VoLTE call setup time is only about 1 second, which is one sixth of the call setup time in 2G, 3G networks, allowing users to get connected immediately after pressing the call key.

About call quality, VoLTE service provides high quality voice (HD voice) to satisfy the most demanding customers. HD voice is a broadband audio technology, the audio frequency range extends from 50 Hz to 7 kHz, while conventional voice calls have a limited audio bandwidth of only 0.3 kHz to 3.4 kHz. As a result, the quality of VoLTE voice calls are much improved, giving customers a better, clearer sound,

At this time, there are more than 500 4G LTE networks in the world, but only about 100 operators are deploying VoLTE services, including major telecommunications brands such as AT & T, T-Mobile, Verizon (USA) China Mobile (China), Reliance Jio, Bharti Airtel (India), Vodafone (UK), ...

In Vietnam, Viettel is going to be the first 4G network to provide high quality VoLTE services. Let's wait for this exciting experience from Viettel's 4G network.