The messaging app has officially added voice calling, a long-teased feature that was previously available only by invitation. WhatsApp users can now call their contacts worldwide for free over a WiFi or 3G/4G connection. After making a name for itself with free text messaging, WhatsApp is breaking into the VoIP market with its latest feature, introduced in the latest update for Android (2.12.19) and soon to come to iOS. The move places WhatsApp in direct competition with Microsoft's Skype and Rakuten's Viber, both of which allow users to make voice calls between online contacts and -- for a fee -- to any number, landline or mobile.



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