Calling feature has been introduced by WhatsApp now. It has been stated that it will be available only for Android KitKat onwards, though I am not sure about this.
First of all you need to have the latest version of WhatsApp for this to work. Check if you have version 2.11.508 or above, else update.
1. Ask someone who has the feature enabled to call you. WhatsApp has enabled the feature for some users as a beta testing.
2. That's all! Your Voice calling feature is enabled. Note:
You can call anyone without this feature now to enable this on their number. which means you can activate
voice calling on other users once it is activated on your account.
The feature has not yet been activated on my account. I have been checking for someone with the feature enabled so that I can ask him to call me and it will be activated on my number as well. Please Note
- This feature can also be activated using some hacks for which you need to root your phone. The process is risky as it may damage your Whatsapp application files.
Refer to this link
in which I have also mentioned the other two unofficial hacks. But please proceed at your own risk