Can't make a free call on Viber.

Question

I can receive Viber messages and calls from my friend through Viber, but I can't call him back (I receive message "Not on viber. Send invitation"). I can only use Viber Out for that friend. Why?

Answer 1

Viber won't show that messages unless your friends isn't on Viber, that's why you can call him using Viber Out only. I didn't see any errors similar to this one. If you receive that message, then it means your friend isn't using Viber and your version of Viber is used as a replacement for Phone and Messages in the device you're using something like Facebook Messenger with SMS support.