A data communication system is disclosed which comprises: first terminal devices for transmitting contents and content provider identification data identifying the providers of the contents; a server device for receiving and storing the transmitted contents and content provider identification data; and second terminal devices which transmit user identification data to the server device, which receive and store the contents from the server device based on the user identification data, and which reproduce the stored contents upon detection of an incoming call. The server device stores first account information corresponding to the content provider identification data and second account information corresponding to the user identification data. The server device increments first amount information in the first account information when receiving the contents from the first terminal devices; the server device decrements second amount information in the second account information when transmitting the contents to the second terminal devices.