Samsung Galaxy S9 and S9+ update adds support for dual VoLTE and VoWiFi
Galaxy S9 and S9+ bring support for dual voice over LTE (VoLTE) and voice over Wi-Fi (VoWiFi). The update weighs in at 425MB and is delivered OTA (over the air) in India, but it should be rolled out in other countries very soon.
Obviously, due to the nature of the changes, the update is very important for the dual-SIM versions of the top-tier phones, so if you own one, you'll want to look for firmware version G960FXXU1BRE5 (Galaxy S9) or G965FXXU1BRE5 (Galaxy S9+).
Besides support for dual VoLTE and VoWiFi, the update also includes some “device stability improvements,” bug fixes, and further improvements to performance.