YOu will have to contact Viber. Look at their support site http://itunes.apple.com/us/app/viber-free-phone-calls-text/id382617920?mt=8
Or look to the right at more like this -----------------> look for the green check mark to find your answer.
This is an official representative of Viber Media.
Please try removing Viber, wait 24 hours, reinstall and try again (make sure you try both the SMS and the automated call options). If this doesn't help, contact our support team at http://support.viber.com and give them the details of the problem.
For more questions or technical support, please visit our official HelpDesk.
I want to inform you that there is an access code problem on Kosovo Vala GSM provider which has the country code of Monaco. Meanwhile, its country code starts with +377 and Vala GSM provider has 44 entry , it means +37744 . So, when we try to get the access code , the automatic system does not send it. Moreover, when we try to use no code option it even does not call us to give the access code.
Additionally, we removed and waited 24 hours, reinstall and tried it again... However , it is same again...