This paper proposes an approach of secure communication through the Internet based on the technology of speech information hiding. In this approach, the algorithm of embedding a 2.4Kbps low-bit-rate Mixexcitation linear prediction (MELP) speech into G.729 coding speech is presented by adapting the techniques of covering code and the interleaving. The parameters in G.729 source codec are analyzed in the Capability of noise tolerance (CNT) and selected to carry secret speech data because these parameters have less impact on the quality of being reconstructed speech. Experiment results show that the proposed steganography algorithm not only gained a high data embedding rate up to 2.4Kbps but also achieved better imperceptibility, which indicates that the algorithm can be used for high data embedding capacity hiding and can achieve good effect.