tailieunhanh - VOIP TECHNOLOGIES

Voice over IP (VoIP) is undoubtedly a powerful and innovative communication tool. Compared with the public switched telephone network (PSTN), VoIP off ers the benefi t of reducing communication and infrastructure cost. This makes it possible for everyone to easily keep in touch with family, friends, and clients around the world. Furthermore, VoIP has the potential to create new and att ractive communication tools by integrating with various applications, such as Web systems, presentation soft ware, and photo viewers | VOIP TECHNOLOGIES Edited by Shigeru Kashihara VoIP Technologies Edited by Shigeru Kashihara Published by InTech Janeza Trdine 9 51000 Rijeka Croatia Copyright 2011 InTech All chapters are Open Access articles distributed under the Creative Commons Non Commercial Share Alike Attribution license which permits to copy distribute transmit and adapt the work in any medium so long as the original work is properly cited. After this work has been published by InTech authors have the right to republish it in whole or part in any publication of which they are the author and to make other personal use of the work. Any republication referencing or personal use of the work must explicitly identify the original source. Statements and opinions expressed in the chapters are these of the individual contributors and not necessarily those of the editors or publisher. No responsibility is accepted for the accuracy of information contained in the published articles. The publisher assumes no responsibility for any damage or injury to persons or property arising out of the use of any materials instructions methods or ideas contained in the book. Publishing Process Manager Jelena Marusic Technical Editor Teodora Smiljanic Cover Designer Martina Sirotic Image Copyright WitR 2010. Used under license from First published February 2011 Printed in India A free online edition of this book is available at Additional hard copies can be obtained from orders@ VoIP Technologies Edited by Shigeru Kashihara p. cm. ISBN 978-953-307-549-5 I kfTC LI OPEN ACCESS INI Evn PUBLISHER INTECH open free online editions of InTech Books and Journals can be found at .