MIUI 9.5.14 update brings the Dual 4G VoLTE to Xiaomi Redmi note 5 pro
Xiaomi started rolling out MIUI 188.8.131.52 (OEIMIFA) update for the Redmi note 5 pro users, it will be rolled out via the OTA method in a phased manner, so you might have to wait a few days to receive it. However users hava the option to manually flash the ROM.
This update brings the Android 8.1 Oreo. This update also brings April security patch to the device along with updated Mi Video with online content integration but Mi Music app is not yet updated and lacks Hungama Integration. This update will enable Dual 4G VoLTE. Sadly, there is no 4K video recording support.
If you didn't received the update notification then go to Settings > About phone > System update > check update.