Whatsapp for windows phone finally got voice calling option

Update your whatsapp with latest updates :

• WhatsApp Calling: Call your friends and family using WhatsApp for free, even if they're in another country. WhatsApp calls use your phone's Internet connection rather than your cellular plan's voice minutes. Data charges may apply. Available on Windows Phone 8+.
• You can now send audio files (available on Windows Phone 8.1+)
  

Click here to download whatsapp update from store