Everyone like free stuff, including me. I like free communications, free calls, sms, messages. It is awesome to know Viber when it first launch as free app as iPhone app. it has been taken quite a while to launch the android version of viber. I started to use Viber beta when it released to some android users. There are alot of free call & messages android app but i choose to Viber as it has more users, Android and iPhone users. I met many of my friend in Viber when i first install Viber, cool. It is really cool ^^
Both Calls & Messages works well with WiFi. Good to have it.