Free online Books and tutorials on IP Telephony and VoIP

Syngress Configuring Cisco VoIP :( free in PDF format ) (BOOK)The book is organized around the configuration of all of Cisco's core VoIP products, including the voice/fax feature card, integrated access system, voice manager, and the voice-enabled Cisco 2600 and 3600 series. Anyone responsible for the actual installation, configuration, and troubleshooting of a Cisco VoIP device will find this book invaluable. As with all Syngress Media books, online chapter updates will be published three to six months after publication. (Link taken From http://www.ssuet.edu.pk/%7Eamkhan/ )

Cisco IP Telephony Network Design Guide :( free in PDF format ) (BOOK)It contains all the concepts related to Cisco IP telephony.(Link taken From http://www.ssuet.edu.pk/%7Eamkhan/ )
Cisco IP Telephony QoS Design Guide :( free in PDF format ) (BOOK)It contains all the concepts related to Cisco IP telephony. (Link taken From http://www.ssuet.edu.pk/%7Eamkhan/ )
IP Telephony Solution Guide :( free in PDF format ) (BOOK)This book teaches all the concepts of IP Telophony (Link taken From http://www.ssuet.edu.pk/%7Eamkhan/ )
Syngress Cisco AVVID & IP Telephony Design & Implementation : ( free in ZIP format ) (BOOK)Cisco AVVID Design and Implementation is a complete reference for network administrators and engineers responsible for a complicated AVVID network. This book covers history, protocols, hardware, servers, switches, bridges, and routers, and discusses implementation issues, realities of cost, requirements, and network limitations. Engineers will learn how to design and build a comprehensive Cisco AVVID network infrastructure. Second in a series, this book is designed as the next-step for readers who have read the well-received Configuring Cisco AVVID Architecture for Voice, Video, and Integrated Data. (Link taken From http://www.ssuet.edu.pk/%7Eamkhan/ )