I have activated VOLTE on my Samsung S9 through a dialog that popped up a couple of weeks ago but since then I seem to be experiencing many more times during the day where my signal drops out completely. I wanted to disable this to test but the option doesn't appear in the settings where I believe it should (Settings->Connections->Mobile Networks).
How can I disable VOLTE?
Can you give the following instructions a shot?
Make sure that you're running on the latest version of Android available for your handset
Let us know how it goes.