I have seen there are some devices ,which can encrypt and decrypt voice over GSM . Ex : http://www.hyperencrypt.com/ . it input data from microphone and output data to headset port. GSM has a lossy compression . So , if voice is encrypted , when transmitting the signal ,some details will lose .So, making it difficult to decrypt it . Is there any algorithm to bypass it ? any algorithm , which takes PCM (Pulse Code Modulation) data and encrypt , receive sound like signal .(and possible to decrypt it) ?