Real-Time Data Transmission over PSTNs on Physical Layer

Widespread use of data communications applications along with recently emerging high-performance telecommunication techniques enforce people, organizations, and even countries to rely on the infrastructures with which these communication services are provided. It is clear that dependence on infrastructure leads to critical concerns about security, reliability, authenticity, and integrity of the data carried over the same infrastructure. Therefore, a prototype based on digital signal processor (DSP) is implemented, which operates on public switched telephone network (PSTN) lines in accordance with the regional (ITU-R, European) standards, supports steganographic information exchange, and allows both analog and digital data transfer in several security levels. In addition, statistical characteristics of the physical layer channel are identified via measurements and communication between two end nodes is established with the use of DSPs by taking into account the behaviors of the switching center. Future directions are provided in light of the results and relevant discussions as well.