The Future Of Telephony Is Now Asterisk The Definitive Guide Introduction This is the online home of Asterisk: The Definitive Guide, a free book about Asterisk, an open source PBX platform that runs primarily on Linux. As you may have guessed from the layout of this page, this book is published by O'Reilly Media. This is a place to read HTML version of the book (you can also buy a copy if you'd li