Today, optimal performance and cost advantages of using Internet telephony are obvious. Despite current standardized techniques, voice transferring through protocol (VoIP) has lower security than traditional telephony. One of the most important security issues which should be noticed in using VoIP is end -to-end user2 identity, i.e. when there is a connection between user A and B, user A should be assured of the identity of user B, and vice versa. The authentication of identity is one of so important information that could guarantee the security and integrity of information [1]. In this study, the security of VoIP and data steganography through the protocol has been investigated. Finally, a technique for data steganography4 over this protocol will be proposed using the method of Residue Number System3. Also, using the combination of RNS, DNA sequences, and Huffman compressing algorithm, an algorithm is proposed for data steganography through VoIP. The algorithm improves security of the process of transmission of hidden text and can use the bandwidth effectively. Manuscript profile