Download viber from the following site:
wget http://download.cdn.viber.com/cdn/desktop/Linux/viber.deb
Install the package using dpkg:
dpkg -i viber.deb
Open it and start using Viber.
If the following error appears after trying to execute Viber.sh on Debian Wheezy manually:
/usr/share/viber/Viber.sh
/usr/share/viber/Viber: /lib/x86_64-linux-gnu/libc.so.6: version `GLIBC_2.24' not found (required by /usr/share/viber/Viber)
You need the latest version of glibc, to do that add the following to /etc/apt/sources.list:
sudo vi /etc/apt/sources.list
deb http://debian.co.il/debian/ testing main
deb-src http://debian.co.il/debian/ testing main
Update apt and install the latest glibc library:
sudo apt-get update
sudo apt-get -t testing install libc6