DiGi 2017 Postpaid user using until 2022, VOLTE & VOWIFI (Also called VoIP) function as normal, My device are Samsung Galaxy A72.

If having VoLTE issue,

Some of the RM0.7k mid end entry device - 1.2k high end entry device are not supported base on chipset

But to be honest, 2022 already... I believe those RM800 phone must comes with those two function.

If your device are not supported, I'm sorry you can't get the those service.

If your device are supported, may have a call to TELCO Service Center hotline to make sure your VOLTE was active,
Back on 2018-2019 DiGi firstly on Malaysia having VOLTE function, when I was using my old Samsung Galaxy A50 which is supported those two function but I didn't see the function active!
I need to call CS hotline to active, and make sure your SIM card are in new patch, old SIM card does not support.

For WOWIFI,
Kindly have a check on your device on the manufacture user manual does your device supported for Vo-WIFI, also the does the router have this function or not?
After 2019, new WiFi required to login into router system to setup VoIP section, also if your using TELCO haven't got VOIP function... you only just wait.... they announcement having that function... hahahaha

Fun fact
still got a lot of people didn't know what is VOLTE & VOIP...