How to make a call from the site using Viber?

Question

HTML

Good afternoon everyone. You need to implement the following, an analogue of the Skype icon for Viber. When you click on a button or a picture located on the site, Viber automatically opens and the call starts. Googled and Yandexil, found nothing. Only one vague answer, that you need to correctly compose a link (and that ended with the phrase "if the developers have provided for this") So that Viber intercepts it, by analogy with Facebook's links that it intercepts and connects to the application - fb://

Answer 1

no way. Viber does not have an open api
update: after 1.5 years! https://habrahabr.ru/post/321246/

Answer 2

Option 1:
viber://add?number=79996665544 - on a smartphone, opens a dialog for adding a new contact in Viber. Opens app on desktop but throws an error.
Option 2:
https://viber.click/79996665544 - after a four-second redirect, immediately opens a chat window with a contact both on a smartphone and on a desktop.