For Samsung S10, please do the following to enable the VoLTE:
Go to the Settings icon.
Tap on Connections.
Choose Mobile Networks.
Tap the status switch beside VoLTE Calls to toggle it on and off.
You can also send me a screenshot of your mobile network settings. To enable the WiFi-Calling feature,
On the Home screen, tap on the Phone icon. Tap the Keypad tab, then tap Menu > Settings. Tap the Wi-Fi calling switch on / off. Make sure your Wi-Fi connection is enabled. The VoLTE will disappear beside the signal bars when you are connected to your wireless home network.
Let me know how it goes.
The issue is it's not working and no one knows how to turn this on. I have 2 services with TPG both have the same problem and its not a handset issue. Who can i contact to get an answer?
If your WiFi calling is enabled, please try to call a number and then send me a screenshot of that call. Then, disable the Wi-Fi calling and see if there will be a VoLTE that will appear beside the signal bars, take a screenshot too and send it via private message.