Use CryptMyCall it's a new AMAZING App that allow u to talk for free..
Is a new secure VoIP phone app which lets you make encrypted phone calls over the Internet using your Android device.
Only one touch and you can call your friends with full protection and privacy.
What is needed is simple: CryptMyCall app on both Android devices
mmm nono u cannot talk for free ... u can encrypt your calls... if u have some flat connection or wireless wimax ecc u can talck for free like all others application voip based.. but this app allow to talk by voip and first of all make sure and encrypted calls!!