Whatsapp calling for windows phone is now availiable in the latest update! Update your whatsapp and start calling your contacts in whatsapp for free. The UI of windows phone whatsapp calling feature seems very clean. Enjoy Whatsapp calling now.
It was a long waiting since android received whatsapp calling feature. Now windows Phone received whatsapp calling feature.
For making a whatsapp call using windows phone just select a contact and from the bottom select the calling button. The call will start immediately.