Many users have been anticipating WhatsApp to finally bring voice calling to its application sometime in 2015, and it looks like the feature is beginning to roll out to some users. The calling, like WhatsApp messaging, uses an internet connection to place a phone call instead of relying exclusively on a carrier’s network to handle the call.
The updated calling interface isn’t available to everyone, but according to some Reddit users, if you already have the update you can get another person in on the voice calling action by placing a call to them, forcing the interface update. WhatsApp hasn’t made anything official just yet, so this is all pure speculation and trial and error.
Regardless, if you’ve been wanting voice calling through the app, you shouldn’t have to wait too much longer. If some users are seeing it, we can probably expect a massive launch for everyone in the near future.