One of the strengths of WhatsCall over other apps like it is that you can earn up to 2,000 credits in a single day – enough to pay for a 30-minute phone call. To get credits you can view announcements, install apps, or even play roulette. Though you can obviously also use real money.
It's important to keep in mind that to create a WhatsCall user account you do need your own phone number. You don't actually need to use the device associated with the number (meaning you can make calls from a tablet, for instance), but you will need to verify the phone number to get set up.
The nice thing about WhatsCall is that you can make free phone calls without relying on any other service like LINE, WhatsApp, or Skype. With all these apps the other people also have to have the app installed, but with WhatsCall you can ring straight through to their phone line.
Android 4.0 or greater is required