install apk to android
download apk to your computer
connect android phone to computer
transfer the downloaded apk to the phone
on phone download (google store) easy installer
in addition:
http://voip.about.com/od/servicesandsolutions/fl/Viber-40-Updates-ndash-Viber-Out-and-Voice-Messaging.htm
experience
5.0.2.12. slow, but it knows video messages, audio messages
3.0.1 good, but it knows just text messages
try