Free voice calls using internet, and threaded text messages for free using WiFi.
Viber is a skype alternate for smartphones. It offers free viber-to-viber calls and text messaging over the internet. Normally you have to register for a VoIP service, and then use some other VoIP software for your handset and specify the VoIP server IP and port settings etc in it to get the service working – a feat which feels too complicated for normal users. Viber is charming in the sense that they have their own app, and you just have to create an account and start using it.
Viber replaces skype’s chat with a more famous threaded bubbles format for sms. Best feature of viber is that it integrates in your phone’s address book. So, you can directly make viber calls and messages from there. And just as easily switch to GSM call if you are getting bad quality over the internet.
Just like skype, viber to viber calls are free and sound quality is slightly better than skype, so if you do have Wifi coverage then Viber really helps you reduce your GSM bill. Viber does have disadvantage over Skype that there is no desktop or symbian client for it. Moreover it only does audio calls and messaging as compared to skype which supports video calling too. So, your contact list of Viber friends can only grow to users of iPhone and Android handsets only.
The app has been available in iPhone for around a year now, and is now available for Android OS 2.0 and higher sets also. Nokia Ovi app is still in development and has been promised to be released later.
Get the Viber app for your phone @ Android Market / iTunes