Viber is one of those sellout services that belong in the world of Android and Apple. They sell your privacy for a cheap service. Though I with great hesitation threw away my privacy when I chose webmail in the mid '90s.
We throw away our privacy by opting in to using mobile phone service and we discard it with email, facebook, and twitter.
Our habits, purchases, and search terms on Amazon and eBay are commodities we trade for good and sometimes even crappy deals.
Nobody could be bothered to include usable crypto plugins for email that we could get our non-geek friends to use and almost nobody could be bothered to implement something radical like freenet.
As for sending to a server in Israel even if the Mosad has a backdoor you are getting less snooped than if you route packets through the US, UK, or commonwealth where the entire raw throughput is stored in bulk rather than passed on by request. Israel just doesn't have the unlimited funds the US and to a lesser extent the UK does even if it wanted to.
I remember a day when a court order was required to tap a phone line, now it just requires a hunch for the interested US or UK agency to to access the already universally tapped stored information.
Maemo was always a dead end as seen on the N770, N800, N810, and N900; too much freedom (as in beer and as in speech) creepy corporate sellout/spy apps are what make the normal iOS and droid universe.