There are random times in a day or week when the Whats App servers are online, and without any notice.
What we mean is that if an active user calls you, you may get activated for the calling feature, only if the activation servers at Whats App’s end are running.
If the servers are down, then you can just get a call, answer and chat, but not get activated.
If you want to proceed, do the following steps: We confirm that the above steps have worked for us. Note: We tried these steps during the day of writing this article and confirmed that it worked on two the smartphones we tried it on.
If you are trying the same, and if it worked for you too, do report the same in the comments below.
This feature was already present with apps such as Google Talk, Skype, now Facebook Messenger, and a lot more.