This is the only Vietnamese network announced by Apple that can use VoLTE and eSIM

VoLTE (Voice over Long Term Evolution) is the standard for high-speed wireless communication on mobile phones and data terminals, helping users to increase call quality with wideband audio and audio frequency bands. The bar is expanded from 50Hz – 7kHz. Meanwhile, regular calls now have an audio band limited only from 0.3kHz – 3.4kHz.

To put it simply, VoLTE is a 4G-based voice technology, providing voice calls with extremely fast connection time, true sound quality in HD. When using VoLTE, users will feel enhanced call quality, with clearer sound, faster connection speed. However, this depends on not only the supported device but also the network that you are using.

With Apple phones, VoLTE can only be used with minimum products from iPhone 6 or higher. Depending on the country, carriers may also offer this service. According to information on Apple's official website today updated, only in Vietnam, Viettel has been confirmed to provide this service.

For ordinary users using Viettel's network service, just text "HDcall" to 191 and these customers will be upgraded to VoLTE completely free.

Viettel is certified by Apple as the only operator in Vietnam to provide eSIM and VoLTE services.

Besides being the only network operator in Vietnam that has been confirmed by Apple on its official website to support eSIM, Viettel is also a successful carrier in eSIM testing on smartwatches without connecting to phones. However, the exact time when smartwatch models in Vietnam will be using eSIM Viettel has not been disclosed.

eSIM is a type of electronic SIM, with physical circuits of very small length and width, less than 5x5mm, soldered directly to the circuit board of the device during production but still has the same functions as regular SIM cards.

When equipped with eSIM, manufacturers can remove the SIM slot, SIM tray and electronic components connected to the SIM. Removing the SIM slot will give the machine no openings for dust, water and impurities to get inside the device's hardware. This compactness is what makes eSIM usable in smart watches.

Currently, eSIM of Viettel can be used on iPhone XS, XS Max and iPhone XR, iPhone 11, iPhone 11 Pro and iPhone 11 Pro Max (models with eSIM support) with iOS operating system from version 12.1 and above. up.