VoIP Hacks

Preface

Voice over IP, or VoIP, is a family of technologies that enables voice applications and telephony to be carried over an Internet Protocol (IP) network such as the Internet. These technologies include protocols, hardware and software standards, and computer programs. VoIP is employed in telephony applications, from analog phones to next-generation IP phones and wireless headsets, and in desktop voice chat services, from web-based party-line chat services (like Yahoo! Chat) to the well-known Skype desktop voice-calling service.

VoIP has become an important technology that is integrating pervasively into the popular culture. It is employed daily to drive new engines of commerce—everything from business-class VoIP-powered calling services to simple desktop chat tools such as Apple’s iChat. Other high-profile companies like eBay, Microsoft, Google, and AT&T offer applications and services that utilize VoIP, too.

These big companies have recognized that the popular culture is moving to VoIP services en masse, even as the telecom industry is being set on its ear by scrappy young VoIP startups like Vonage, Packet8, and SpeakEasy.net. VoIP services deliver telephony applications less expensively than the old phone companies can hope to. This is because VoIP is free of the continually burdensome legacy technology investment the old phone companies must make to keep the “old” global phone network running. VoIP is also free of the endless government regulations and tariffs imposed upon the old phone companies.

In a nutshell, the way society looks at the voice network has changed. VoIP is the enabler of the change, and tomorrow’s global voice network is the Internet.

This book contains only a small subset of VoIP knowledge—enough to serve as an introduction to the world of VoIP and teach you how to use it to save money, be more productive, or just impress your friends. My friends love my on-hold music when they call my house; I love that when people call my house, the call is connected to my notebook PC via Skype, no matter where I am in the world. You’ll learn how to do all of this and more. I hope this book gets your mental gears turning and that your VoIP hacks are as enjoyable to implement and customize as they were for me to write!

For more VoIP theory and detailed reference information about Voice over IP, check out these great O’Reilly titles:

• Switching to VoIP

• Skype Hacks

• Talk Is Cheap

• Asterisk: The Future of Telephony

• Practical VoIP Using Vocal

Why VoIP Hacks?

The term hacker has a bad reputation in the press. They use it to refer to someone who breaks into systems or wreaks havoc with computers as their weapon. Among people who write code, though, the term hack refers to a “quick-and-dirty” solution to a problem, or a clever way to get something done. And the term hacker is taken very much as a compliment, referring to someone as being creative, having the technical chops to get things done. The Hacks series is an attempt to reclaim the word, document the good ways people are hacking, and pass the hacker ethic of creative participation on to the uninitiated. Seeing how others approach systems and problems is often the quickest way to learn about a new technology.

Since it is based in software, VoIP is overflowing with hack potential. If you love to tinker and optimize, this technology offers a cornucopia of exciting things to tweak and customize. As in the heyday of the World Wide Web, fortunes will be made in the nascent VoIP industry, and lots of fun will be had by voice hackers like you and me.

How This Book Is Organized

You can read this book from cover to cover if you like, but each hack stands on its own, so feel free to browse and jump to the different sections that interest you most. If there’s a prerequisite that you need to know about, a cross-reference will guide you to the right hack.

The book is divided into seven chapters, organized by subject:

Chapter 1, Broadband VoIP Services

In this chapter, you’ll be introduced to some Internet-based VoIP phone service providers who can help you replace your traditional phone line with a cost-saving, feature-rich VoIP line.

Chapter 2, Desktop Telephony

Since VoIP is rooted in software, it has some wonderful uses on your desktop PC or Mac. In this chapter, you’ll learn how to customize and maximize productivity-enhancing telephony applications.

Chapter 3, Skype and Skyping

Skype, the ubiquitous desktop voice-calling application, is one of the most hackable desktop telephony tools, and therefore is worthy of an entire chapter of hacks.

Chapter 4, Asterisk

Just as VoIP enables desktop telephony, it also enables enterprise telephony. In this chapter, you’ll learn how to install, configure, and hack Asterisk, an open source PBX.

Chapter 5, Telephony Hardware Hacks

VoIP is rooted in software, but it is used with lots of different kinds of hardware—everything from next-generation IP phones to old-school rotary phones. This chapter shows you how to add these devices to your VoIP setup—and how to customize them.

Chapter 6, Navigate the VoIP Network

Voice over IP is carried over the network using packets, just like traditional data. With the advice in this chapter, you can monitor VoIP and troubleshoot it using traditional admin tools.

Chapter 7, Hard-Core Voice

By the time you reach this chapter, you will have advanced to the hallowed ground that’s held by a very exclusive crowd: the community of hard-core voice hackers.

Conventions Used in This Book

The following is a list of the typographical conventions used in this book:

Italics

Used to indicate URLs, filenames, filename extensions, and directory/folder names. For example, a path in the filesystem will appear as /Developer/Applications.

Constant width

Used to show code examples, the contents of files, console output, as well as the names of variables, commands, and other code excerpts.

Constant width bold

Used to show user input in code and to highlight portions of code, typically new additions to old code.

Constant width italic

Used in code examples and tables to show sample text to be replaced with your own values.

Gray type

Used to indicate a cross-reference within the text.

You should pay special attention to notes set apart from the text with the following icons:

Tip

This is a tip, suggestion, or general note. It contains useful supplementary information about the topic at hand.

Warning

This is a warning or note of caution, often indicating that your money or your privacy might be at risk.

The thermometer icons, found next to each hack, indicate the relative complexity of the hack:

beginner

moderate

expert

Using Code Examples

This book is here to help you get your job done. In general, you may use the code in this book in your programs and documentation. You do not need to contact us for permission unless you’re reproducing a significant portion of the code. For example, writing a program that uses several chunks of code from this book does not require permission. Selling or distributing a CD-ROM of examples from O’Reilly books does require permission. Answering a question by citing this book and quoting example code does not require permission. Incorporating a significant amount of example code from this book into your product’s documentation does require permission.

We appreciate, but do not require, attribution. An attribution usually includes the title, author, publisher, and ISBN. For example: "VoIP Hacks by Ted Wallingford. Copyright 2006, O’Reilly Media, Inc., 0-596-10133-3.”

If you feel your use of code examples falls outside fair use or the permission given above, feel free to contact us at [e-mail].

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