Being related to end-to-end safety comm area in global mobile comm system, concretely the invention is related to end-to-end speech sound encryption unit and method of anti vocoder compression realized on traditional voice channel of GSM mobile comm system. The encryption unit is composed of encryption module at sending end and decryption module at receiving end. The encryption module at sending end includes compression module in low code rate (CMLCR) 4, an encryption module, orthogonal multicarrier modulation module (OMMM) 6, first carrier wave generator module (CWGM), first key management negotiation module (KMNM) 8, and first sync module. Decryption module at receiving end includes OMMM 14, second CWGM, decryption module, CMLCR 17, KMNM 18, and second sync module. Through GSM speech sound channel, the invention carries out end-to-end speech sound encryption transmission. Advantages are low time delay, high security, and flexible and convenient.