ABSTRACT: This document is your guide to securing the communications infrastructure.

Telecommunications is the backbone of business and domestic life. Instant and reliable communications are imperative to our nation's critical infrastructures such as finance, power, water, and transportation. Ensuring the availability of service has never been more important, especially given the need for increased security in support of Homeland Defense. This Special Report (SR) from Telcordia is your guide to protecting and securing the Public Switched Network (PSN) - the network that provides circuit-switched services among all public users and includes packet-switched public data networks and services.

Protection of the PSN is a matter of national security, as the Office of Homeland Security, the President's Commission on Critical Infrastructure Protection, the Network Security Force, the National Security Telecommunications Advisory Committee (NSTAC), and other prominent Commissions have made clear. You, as a carrier, network owner, or other telecommunications participant, are charged with providing this valuable protection. Understanding how to provide it, despite the many complicating factors, is imperative.

The PSN is the hub of communications that enable the elements of the economy to prosper. The social and economic changes in the last decade have put the security, integrity, and availability of this critical infrastructure in jeopardy.

Security threats are not one-time problems that can be dealt with all at once and forgotten. Like a biological virus, the threats evolve to take advantage of the environment and existing vulnerabilities, and they can never be completely eliminated. Therefore, all stakeholders must exercise constant awareness, vigilance, and action to protect the users of PSN services. This report is based on Industry Standards, Methodologies, and Practices that have been developed to address the multitude of security that exist in this complex network and will get you started in the right direction. With this document, you will learn:

• The basics of PSN security
• The elements of a security policy
• How to assess PSN security

• Transmission Control Protocol (TCP)/ Internet Protocol (IP)
• Asynchronous Transfer Mode (ATM)
• Digital Subscriber Line (DSL)
• Local Number Portability (LNP)
• Next Generation Network (NGN)