Using the "what's app" on Carnival

I am going to purchase a wifi package on my cruise and would like to know if I can place calls home using this app?

The far better place for your research would be the Carnival board, here:

http://boards.cruisecritic.com/forumdisplay.php?f=215

WhatsApp allows you to call other WhatsApp users but I don't know what the rules or feasibility regarding VoIP are on the ship.

From https://www.carnival.com/FunShops/item/SRA/social-wi-fi-plan:

The Social WiFi plan let's you access popular social networks including Facebook, Instagram and Twitter so you can post pictures or your trip and make your friends jealous.

Access these social and chat apps:

• Facebook
  
• Instagram
  
• Twitter
  
• LinkedIn
  
• Facebook Messenger
  
• WhatsApp
  

as well as the most popular airline sites:

• American Airlines
  
• Delta
  
• United
  
• Southwest
  
• Spirit
  
• Jet Blue
  
• Virgin America
  
• Air Canada
  
• Alaska Air
  
• Westjet
  
• Hawaii Airlines
  
• Allegiant
  

However, note the following:

On my last cruise Christmas 2016 we were not able to use the calling feature of what's app. Messaging worked perfectly however