Joshua Brashars 
Asterisk Hacking [PDF ebook] 

Asterisk Hacking provides detials of techniques people may not be aware of. It teaches the secrets the bad guys already know about stealing personal information through the most common, seemingly innocuous, highway into computer networks: the phone system. This book provides detials to readers what they can do to protect themselves, their families, their clients, and their network from this invisible threat. Power tips show how to make the most out of the phone system for defense or attack. – Contains original code to perform previously unthought of tasks like changing caller id, narrowing a phone number down to a specific geographic location, and more!- See through the eyes of the attacker and learn WHY they are motivated, something not touched upon in most other titles.