The new version of Viber on Android lets you block a number or a contact, so you won’t receive any message or call from them (and you even don’t notice). To add a number (or contact) to blacklist on Viber for Android, do as follows:
To block a contact on Viber Android:1. Open Viber application (make sure you have the updated version)2. In your contact list, open the contact you want to Block.3. Tap the 3dot icon on the top right and tap the Block option.
To block a number on Viber Android:1. Open Viber application (make sure you have the updated version)2. Go to Viber Settings.3. Open Privacy menu4. Tap on “Block List”5. Use the “+ Block Number” icon on the bottom center to insert a number and add it to your blacklist
To Unblock a contact/number on Viber and view the list of blocked persons:1. Go to Viber Settings.2. Tap on “Privacy” followed by “Block List”4. List of blocked contacts/numbers are shown5. Use the Unblock button to remove your contacts/numbers from the black list.