Practical VoIP Security
Written for the thousands of IT professionals who are now responsible for deploying and maintaining secure VoIP networks, this book covers evaluation, design, integration, and management of VoIP networking components.
TABLE OF CONTENTS Practical VoIP Security
Chapter 3: The Hardware Infrastructure
Introduction
Even after the introduction of VoIP, business telephony equipment has remained focused on two areas: (1) reducing the cost of Public Switched Telephone Network (PSTN) connectivity overall and (2) adding business communications feature-functionality. Since the first private branch exchange (PBX) was introduced in 1879, business customers have sought cost savings by reducing the number of physical lines or trunks that interconnect with the PSTN. Because most calls in a large organization remain within it, cost and security benefits accrue immediately by placing a telephone switch inside the organization. And with the introduction of digital switching nearly a century later, a new wave of feature-functionality became possible. For the first time in history, the enterprise telephony capabilities would surpass that offered directly by PSTN carriers. In some respects, the latest developments in VoIP are an extension of this pattern.
| Note | The basic architecture of the PBX over the past 100 years has evolved similarly to that of the PSTN and its switches overall. If you re interested in that evolution and how it has influenced today s PBX designs, you may want to read Chapter 4 before reading this chapter. Otherwise, consider this chapter to be a discussion of PBX architecture during the past decade and the interaction between the digital PBX and its VoIP equivalents. |
From a security perspective, it s important to distinguish between several different architecture models for business and consumer telephony. On the low end, Key Telephone Systems (KTS) for up to 50 users provide a very basic means...
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