Cellcrypt Mobile for iPhone works with iOS4 on Apple’s iPhone 3GS and iPhone 4. It’s a VOIP (voice over IP) application that uses either Wi-Fi or an operator’s data channel on either GPRS, EDGE, 3G or satellite networks to transmit voice. Both the caller and the recipient must have Cellcrypt installed in order to encrypt the call. Cellcrypt uses public key cryptography, and each phone running its software has its own private key stored only on the device.”]