I'm having terrible problems with Viber. I have 4S, and until the last month could make calls locally, or internationally. Now, I can no longer make calls through Viber. Skype works fine, but Viber cannot complete calls. It always says "Call Failed". I uninstalled and then reinstalled Viber and the problem persists. Yes I did change all the numbers to international numbers, no dice. I can send text messages fine through Viber, but can't call anyone! I have also tried downloading Viber on my laptop (W7), and it won't install. It gets into a loop for about an hour saying that installation files are installing, and then nothing. What is it with Viber that they offer no technical assistance on their website, other than FAQs and instructions? Its odd we have to go to other forums to get support for things they don't cover. I'm just about done with Viber because of its problems! This is my last resort, if I can't fix the problems, I'll just uninstall and just use Skype - which seems to work better anyway. I am in China at the moment, but wouldn't think that has anything to do with my issues with Viber.