Viber has done some changes to the Android version application and also has released a Desktop version too. With Viber you can make voice calls from your Android smartphone to your PC and it also supports voice chat.You can send messages too and all this for free.
But how to sync your PC app with the Android app?Well it is a very simple process.
After you have installed Viber in your PC,it will ask you if you have installed Viber in your smartphone.If yes,it will send you a code to your smartphone and then you will have to paste this code to the PC app.After you paste the code,everything will start to sync:contacts,messages and calls log.
Download Viber for PC/MAC here