WhatsApp is expected to introduce the calling feature in its app soon. This feature will allow people to talk to their WhatsApp contacts using the cellular data connection or Wi-Fi. This means they won't have to pay for the call charges. Only the data charges will apply, irrespective of where you are calling.
This is similar to Skype or Viber. But considering the user base of WhatsApp it is a big deal.
The feature is not yet officially available. But there are people using the calling feature in WhatsApp and you too get it now, with a little bit of luck.
But before we talk about the luck part, this is what you have to do to get the calling feature in WhatsApp:
-- You must have an Android phone that is running Android Lollipop. In fact at this moment, we are not even sure if the feature works on the non-Nexus phones or not. So it is even better if you have Android Lollipop on a Nexus device.
-- Uninstall WhatsApp.
-- Go to WhatsApp.com and download the app from there. This means you will get the latest app. This is an APK file.
-- If you know how to install the APK file install it. If not, follow these steps: Got to Android Play Store > Install ES File Explorer > Open ES File Explorer > Go to the downloaded APK > Install WhatsApp APK
-- Once you have the latest version of WhatsApp and if your phone has Android Lollipop, you need to find someone who has already got the WhatsApp calling feature. Ask around, ask your friends on Twitter and Facebook if any of them have the calling feature.
-- Ask the person who already has the WhatsApp feature activated to give you a WhatsApp call.
Now here is the luck part. The feature doesn't get activated for everyone. It looks like WhatsApp is still testing it and even the users who get call from someone who already has WhatsApp calling feature are getting it randomly. Chances are that once you get a WhatsApp call, you too will probably get the feature. But if you don't, then you will have to wait for a few more weeks. It is expected that the calling feature in WhatsApp will be available soon.