Backup AND RESTORE of viber messages

Since this is old question but someone maybe still wonder how to do it now there is option to do that manually and automatically. Everything you have to need is that you are logged in with Google account, and simply go to viber >settings>account>viber backup, you can select a Google account on which you want backups to be stored and than choose how often you want backups or do that manually by pressing 'backup', there is also restore option and by the way restore option will be offered automatically when you install viber if Google account in use have backup on it. Here is a video of how to do it:

https://www.youtube.com/watch?v=ISWywTUB2-M