Real time data transmission over GSM voice channel for secure voice and data applications

This paper describes a real time prototype implementation of a system, which enables secure voice and data communication over the GSM voice channel. The security of GSM is not guaranteed especially over the core network. The proposed system modulates digital data, which may be encrypted onto speech-like waveforms. The modulated waveform is then transmitted over the GSM voice channel, which can be demodulated and decrypted at the receiver. The real time prototype system has been tested on GSM-to-GSM voice calls, and a proprietary speech codec is used on the real time data channel to produce communication quality speech. A demonstration will be provided at the presentation.