Switching to VoIP (Paperback)

Theodore Wallingford

  • 出版商: O'Reilly
  • 出版日期: 2005-07-26
  • 定價: $1,320
  • 售價: 9.0$1,188
  • 語言: 英文
  • 頁數: 502
  • 裝訂: Paperback
  • ISBN: 0596008686
  • ISBN-13: 9780596008680
  • 立即出貨 (庫存=1)




More and more businesses today have their receive phone service through Internet instead of local phone company lines. Many businesses are also using their internal local and wide-area network infrastructure to replace legacy enterprise telephone networks. This migration to a single network carrying voice and data is called convergence, and it's revolutionizing the world of telecommunications by slashing costs and empowering users. The technology of families driving this convergence is called VoIP, or Voice over IP.

VoIP has advanced Internet-based telephony a viable solution, piquing the interest of companies small and large. The primary reason for migrating to VoIP is cost, as it equalizes the costs of long distance calls, local calls, and e-mails to fractions of a penny per use. But the real enterprise turn-on is how VoIP empowers businesses to mold and customize telecom and datacom solutions using a single, cohesive networking platform. These business drivers are so compelling that legacy telephony is going the way of the dinosaur, yielding to Voice over IP as the dominant enterprise communications paradigm.

Developed from real-world experience by a senior developer, O'Reilly's Switching to VoIP provides solutions for the most common VoIP migration challenges. So if you're a network professional who is migrating from a traditional telephony system to a modern, feature-rich network, this book is a must-have. You'll discover the strengths and weaknesses of circuit-switched and packet-switched networks, how VoIP systems impact network infrastructure, as well as solutions for common challenges involved with IP voice migrations. Among the challenges discussed and projects presented:

  • building a softPBX
  • configuring IP phones
  • ensuring quality of service
  • scalability
  • standards-compliance
  • topological considerations
  • coordinating a complete system ?switchover?
  • migrating applications like voicemail and directory services
  • retro-interfacing to traditional telephony
  • supporting mobile users
  • security and survivability
  • dealing with the challenges of NAT

    To help you grasp the core principles at work, Switching to VoIP uses a combination of strategy and hands-on "how-to" that introduce VoIP routers and media gateways, various makes of IP telephone equipment, legacy analog phones, IPTables and Linux firewalls, and the Asterisk open source PBX software by Digium. You'll learn how to build an IP-based or legacy-compatible phone system and voicemail system complete with e-mail integration while becoming familiar with VoIP protocols and devices. Switching to VoIP remains vendor-neutral and advocates standards, not brands. Some of the standards explored include:
    • SIP
    • H.323, SCCP, and IAX
    • Voice codecs
    • 802.3af
    • Type of Service, IP precedence, DiffServ, and RSVP
    • 802.1a/b/g WLAN

      If VoIP has your attention, like so many others, then Switching to VoIP will help you build your own system, install it, and begin making calls. It's the only thing left between you and a modern telecom network.


Table of Contents:



1. Voice and Data: Two Separate Worlds?

     The PSTN

     Key Systems and PBXs

     Limits of Traditional Telephony

     VoIP in the Home

     VoIP in Business

     VoIP's Changing Reputation

     Key Issues: Voice and Data: Two Separate Worlds

2. Voice over Data: Many Conversations, One Network

     VoIP or IP Telephony

     Distributed Versus Mainframe

     Key Issues: Voice over Data: Many Conversations, One Network

3. Linux as a PBX

     Free Telephony Software

     Installing Legacy Interface Cards

     Compiling and Installing Asterisk

     Monitoring Asterisk

     Key Issues: Linux as a PBX

4. Circuit-Switched Telephony

     Regulation and Organization of the PSTN

     Components of the PSTN

     Customer Premises Equipment

     Time Division Multiplexing

     Point-to-Point Trunking

     Legacy Endpoints

     Dial-Plan and PBX Design

     Key Issues: Circuit-Switched Telephony

5. Enterprise Telephony Applications

     Application Terminology

     Basic Call Handling

     Administrative Applications

     Messaging Applications

     Advanced Call-Handling Applications

     CTI Applications

     Key Issues: Telephony Applications

6. Replacing the Voice Circuit with VoIP

     The "Dumb" Transport

     Voice Channels

     Key Issues: Replacing the Voice Circuit with VoIP

7. Replacing Call Signaling with VoIP

     VoIP Signaling Protocols





     Cisco SCCP

     Heterogeneous Signaling

     Key Issues: Replacing Call Signaling with VoIP

8. VoIP Readiness

     Assessing VoIP Readiness

     Business Environment

     Network Environment

     Implementation Plan

     Key Issues: VoIP Readiness

9. Quality of Service

     QoS Past and Present

     Latency, Packet Loss, and Jitter


     802.1q VLAN

     Quality of Service

     Residential QoS

     Voice QoS on Windows

     Best Practices for Quality of Service

     Key Issues: Quality of Service

10. Security and Monitoring

     Security in Traditional Telephony

     Security for IP Telephony

     Access Control

     Software Maintenance and Hardening

     Intrusion Prevention and Monitoring

     Key Issues: Security and Monitoring

11. Troubleshooting Tools

     VoIP Troubleshooting Tools

     The Three Things You'll Troubleshoot

     SIP Packet Inspection


     When, Not if, You Have Problems-

     Simulating Media Loads

     Key Issues: Troubleshooting Tools

12. PSTN Trunks

     Dial-Tone Trunks

     Routing PSTN Calls at Connect Points

     Timing Trunk Transitions

     Key Issues: PSTN Trunks

13. Network Infrastructure for VoIP

     Legacy Trunks

     VoIP Trunks

     WAN Design

     Disaster Survivability

     Metro-Area Links

     Firewall Issues

     Peer-by-Peer Codec Selection

     Key Issues: Network Infrastructure for VoIP

14. Traditional Apps on the Converged Network

     Fax and Modems

     Fire and Burglary Systems

     Surveillance Systems and Videoconferencing

     Voice Mail and IVR

     Emergency Dispatch/911

     Key Issues: Traditional Apps on the Converged Network

15. What Can Go Wrong?

     Common Problem Situations

     Key Issues: What Can Go Wrong?

16. VoIP Vendors and Services

     Softphones and Instant Messaging Software


     Other Desktop Telephony Software

     Developer Tools and SoftPBX Systems

     VoIP Service Providers

     Telephony Hardware Vendors

17. Asterisk Reference

     How Asterisk Is Supported

     Asterisk's Configuration Files

     Asterisk Dial-Plan

     Asterisk Channels

     The Asterisk CLI

     Integrating Asterisk with Other Software

     Key Issues: Asterisk Reference

A. SIP Methods and Responses

B. AGI Commands

C. Asterisk Manager Socket API Syntax