As far as i know if your device is not VoLTE capable it's not possible, it will only be possible if Dito would have 3g and 2g signals but unfortunately they jumped in to 4g right away therefore there are devices that don't support the telco but try to do a research as to how you could possibly enable the VoLTE on your device bc on my mother's phone it ain't working too i had to do some things just to enable the VoLTE.