The authors have developed an accurate indoor positioning system with an error of just a few cm by using sound. It is possible to a realize data transmission function since the sound wave is the same as the radio wave. This paper presents the method and a new system that achieves both positioning of plural sound sources (user terminals) and data transmission from each sound source using the same configuration. The sound source is modulated based on sensor data before the spread spectrum process. On the receiving side, the positioning calculation is carried out by using the timing of the reception, which is obtained by correlation calculation, and data extraction is conducted by inverse diffusion and demodulation of the received signal. Software design, development and implementation were conducted for the reception operation, and a sound transmitter was developed to complete the experimental system. System performance was evaluated with experiments carried out in both quiet and noisy environments, and the results established the validity of the proposed methods.