People who use Whatsapp on their iPhones will be
delighted to know that an update has just been
released that adds calling functionality over
Whatsapp. The update also brings in several other
improvements.

However the calling feature is not yet enabled for
users yet or at least not for all users. Like on
Android , they need to activate it from their end. So
users who update their Whatsapp version to 2.12.1
will readily get whatsapp calling once they activate
it. Whatsapp says that the feature will roll out slowly over the next several weeks.