Data to Sound Cell Phone Transmition (URGENT)

The project consists in data transmition from one peer to another using a cell phone as a carrier. The data has to be converted to sound because the transmitter has to deliver the data to the cel phone in this format. Then, the cell phone delivers this sounds to the other peer that interprets this sound, converts it back to it’s original format and deliver it to a MCU thru RS232 or I2C interface. The development consists in build the transmitter that will - Receive the data to sent from the MCU thru RS232 or I2C - Convert this data to sound. - Transmit this sound thru it’s own speaker to a cell phone. - The cell phone (that should be already connected to a PSTN line) has to listen to the transmitter and be the carrier to send the data. - On the other peer should be a receiver, here the task is to interpret the package sent by the cell phone and deliver it as the original data to the MCU thru RS232 or I2C. - The receiver unit, has to send back some ACK signal and some other data to the cell phone thru the line. - The cell phone has to deliver that sound to the transmitter’s built in microphone. - The transmitter has to interpret back this data and deliver it to the MCU that generated the original package thru RS232 or I2C. - Of course there will be necessary to build a simple protocol to communicate between the MCU and the Transmitter unit and also the MCU and the Receiver unit. - Another characteristic is that this has to work with any cell phone and both technologies (GSM and CDMA). - Both modules (Transmitter and Receiver) are basically the same, with the difference that the Transmitter is connected to a speaker and a microphone to communicate with the Cell Phone. By the other hand, the Receiver is connected to the PSTN (telephone line) to communicate with the Cell Phone. - We can provide PCBs for testing purposes. (You provide gerber files) - Te maximum data to be transmitted in both directions will be no more than 100Bytes - See attached picture for more details