Source: snapvoip.blogspot.com

O’Reilly Media has released the Asterisk: The Future Of Telephony under under the Creative Commons license. Kudos goes to O’Reilly Media and the three authors, Jim Van Meggelen, Jared Smith, and Leif Madsen. Download links and Authors links are under the links at the bottom of the post.
Once I know the rules, I will post it in IPTELEPHONY in Google Groups.
Asterisk: FOT has received wide attention in the VoIP and IPPBX realm. It is a very well put together book that appeals to new comer to Asterisk as well as to the IPPBX pro. For information, I have listed the contents of the book below.

Contents of the Asterisk: The future of Telephony
Foreword

Preface

1. A Telephony Revolution
VoIP: Bridging the Gap Between Traditional Telephony and Network Telephony
Massive Change Requires Flexible Technology
Asterisk: The Hacker’s PBX
Asterisk: The Professional’s PBX
The Asterisk Community
The Business Case
This Book

2. Preparing a System for Asterisk
Server Hardware Selection
Environment
Telephony Hardware
Types of Phone
Linux Considerations
Conclusion

3. Installing Asterisk
What Packages Do I Need?
Obtaining the Source Code
Compiling Zaptel
Compiling libpri
Compiling Asterisk
Installing Additional Prompts
Updating Your Source Code
Common Compiling Issues
Loading Zaptel Modules
Loading libpri
Loading Asterisk
Directories Used by Asterisk
Conclusion

4. Initial Configuration of Asterisk
What Do I Really Need?
Working with Interface Configuration Files
FXO and FXS Channels
Configuring an FXO Channel
Configuring an FXS Channel
Configuring SIP
Configuring Inbound IAX Connections
Configuring Outbound IAX Connections
Debugging
Conclusion

5. Dialplan Basics
Dialplan Syntax
A Simple Dialplan
Adding Logic to the Dialplan
Conclusion

6. More Dialplan Concepts
Expressions and Variable Manipulation
Dialplan Functions
Conditional Branching
Voicemail
Macros
Using the Asterisk Database (AstDB)
Handy Asterisk Features
Conclusion

7. Understanding Telephony
Analog Telephony
Digital Telephony
The Digital Circuit-Switched Telephone Network
Packet-Switched Networks
Conclusion

8. Protocols for VoIP
The Need for VoIP Protocols
VoIP Protocols
Codecs
Quality of Service
Echo
Asterisk and VoIP
Conclusion

9. The Asterisk Gateway Interface (AGI)
Fundamentals of AGI Communication
Writing AGI Scripts in Perl
Creating AGI Scripts in PHP
Writing AGI Scripts in Python
Debugging in AGI
Conclusion

10. Asterisk for the Гњber-Geek
Festival
Call Detail Recording
Customizing System Prompts
Manager
Call Files
DUNDi
Conclusion

11. Asterisk: The Future of Telephony
The Problems with Traditional Telephony
Paradigm Shift
The Promise of Open Source Telephony
The Future of Asterisk

A. VoIP Channels

B. Application Reference

C. AGI Reference

D. Configuration Files

E. Asterisk Command-Line Interface Reference

Index

Links;
download book as a single entity,a PDF file.(4.5MB) USA1 USA2 UK NL
Download each chapter is a seperate PDF file (3.1MB) USA1 USA2 UK NL
O’Reilly Media
Jim Van Meggelen
Jared Smith
Leif Madsen