Why do I see iPlum audio in my iPhone recents?

iPlum app is built with latest iOS features. The new features allow you to receive iPlum call in locked screen like a normal iPhone call even if the iPlum app is active or killed in the background.  The new feature automatically wakes it up and connects the calls.

That also puts each call in the iPhone Recents as "iPlum Audio".  These Recents are not shown in Carrier billing.  This is something inherent to the iOS and can't be switched off.