Asterisk is an open source software solution that allows businesses and organizations to create their own Private Branch Exchange (PBX) phone system, implement ... » 

Asterisk is an open source software solution that allows businesses and organizations to create their own Private Branch Exchange (PBX) phone system, implement VoIP (Voice over Internet Protocol, or Internet telephony), and drastically slash their phone bills!Digium, the company founded by Asterisk creator Mark Spencer, reports that Asterisk implementations grew over 1,000 percent in 2004, and over 200 telecom suppliers now offer Asterisk solutionsUnlike other Asterisk books, this guide focuses on real-world troubleshooting tips and system maintenance, with a heavy emphasis on VoIP, the main money-saving impetus for organizations using AsteriskProvides coverage of Asterisk hardware requirements, installation, and configuration as well as setting up VoIP functionality and converting calls from VoIP to non-VoIP «