This WhatsApp news really is BIG news
Free internet calling has become a reality with the new (April 02 2015) WhatsApp updates. If you have the Call feature, then you'll see the three columns as above here... and you can start calling any of your friends who are also enabled...
In short, WhatsApp has suddenly become essential.
WhatsApp has already revolutionised the chat/messaging world and now it's directly challenging both cellular and VOIP.