Enable Whatsapp Calling

Step-1: Install the WhatsApp apk from their site

Step-2: Navigate to data/data/com.whatsapp/shred_prefs/com.whatsapp_preferences.xml
Note: Root files access needed to be enabled.

Step-3: Add the following  within the < map > < / map >and save:
C__Data_Users_DefApps_AppData_INTERNETEXPLORER_Temp_Saved Images_whatsapp-calling-feature (10)

Step-4: Go to Settings/Apps/Whatsapp and force stop it

Step-5: Start WhatsApp again

Note: WhatsApp call servers are down, so while you get the feature you need to wait for them to be up to actually use it