WhatsApp calling feature is now busy rolling out to Android users. To get the feature, Android phone users need to update the app to the latest version and then find out a friend who already has the feature.
If someone who already has the WhatsApp calling feature tries to call a user who has the older version of the app, the message tells the user that the app needs to be updated.
The 2.11.528 version of WhatsApp supports calling. Currently, it is not clear if Android Lollipop is required for the feature or not. Earlier, when WhatsApp was testing this feature in a limited way, it worked only on Android phones running the Lollipop.
As it happens in other messaging apps, for the calls made using WhatsApp users will be charged only for the data consumption. They will not be charged for “call charges” that they have to pay for the regular calls.
While calling feature is available with WhatsApp Version 2.11.528, it is buggy. For the better experience, use the Version 2.11.531, which is available directly from WhatsApp website