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In this letter, we propose to perform concurrent data transmissions through analog speech channels using a data hiding technique. In particular, concurrent data are modulated into a noise-like signal and imperceptibly embedded into voices. Conventional embedding methods usually treat speech as a source of interferences to the simultaneously transmitted data. The proposed scheme exploits the knowledge of the speech signal during embedding. Therefore, such an interference can be effectively removed, and a higher data rate can be achieved. Besides, the proposed scheme is compatible with conventional phone terminals. A conventional telephone set is still able to access the basic voice service, while the added decoding mechanism can extract the embedded data and provide various concurrent services. The performance of the proposed method is analyzed. Experimental results demonstrate that an acceptable data rate and bit-error rate can be achieved.