Recents screen displays a list of all your incoming & outgoing calls (Sim and WiFi). This list includes all calls whether they are 'Sim' calls or 'WiFi' calls. Sim (Audio Call) means a call with a real phone number, and not with '+T 123'. On the other side, WiFi - Audio/Video Call means a call with another TextApp user through a number starting with +T 123.

WiFi - your conversation with another TextApp user (whose number starts with '+T 123').
Sim - your conversation with a real number, using your Private Number.