Chapter 5. The Public Network

The public switched network is considered a strategic asset by the U.S. government. It is judged so vital that the U.S. Post Office ran AT&T during World War I. Because of the strategic value of the network, the FCC tracks the reliability of carriers' networks. Messages about public safety, natural disasters and public emergencies depend on reliability in the public switched network.

This chapter reviews circuit switching, dedicated services and signaling system 7. While new networks are being constructed to handle high-speed data, voice and Internet-based services more efficiently, circuit switching is still the primary vehicle for carrying voice, facsimile and dial-up modem traffic. Chapter 9 looks at Internet Protocol-based networks.