At present, voice encryption technology is mainly divided into analog voice encryption and digital voice encryption in two ways.

Analog voice encryption is also called analogue scrambling, which turn the intelligible signal into unintelligible by destructing the original feature of speech through the voice signal frequency domain scrambling, time domain scrambling or a mixture of the two, in order to achieve the purpose of voice signal confidentiality.

Digital voice encryption is to digitize the input speech analog signal and fuse the digital key for encryption protection.

The encrypted voice signal still bear the properties of human speech and can be easily broken whatever methods the analog voice encryption take, frequency domain scrambling, time domain scrambling or a mixture of the two. While digital voice encryption is encrypts the digitalized data, which encryption strength and crack difficulty are far more than analog voice encryption technique, is the only that can really be called “encryption” voice protection technology.