ich may include electronic versions and/or custom covers and content particular to your business, training goals, marketing focus, and branding interests. For more information, please contact: U.S. Corporate and Government Sales (800) 382-3419 corpsales@pearsontechgroup.com For sales outside the United States, please contact: International Sales international@pearson.com Visit us on the Web: informit.com/ph Library of Congress Cataloging-in-Publication Data Dodd, Annabel Z. The essential guide to telecommunications / Annabel Z. Dodd.-5th ed. p. cm. Includes bibliographical references and index. ISBN-13: 978-0-13-705891-4 (pbk. : alk. paper) ISBN-10: 0-13-705891-8 (pbk. : alk. paper) 1. Telecommunication. I. Title. TK5101.D54 2012 384-dc23 2012011366 Copyright © 2012 Annabel Z. Dodd All rights reserved. Printed in the United States of America. This publication is protected by copyright, and permission must be obtained from the publisher prior to any prohibited reproduction, storage in a retrieval system, or transmission in any form or by any means, electronic, mechanical, photocopying, recording, or likewise. To obtain permission to use material from this work, please submit a written request to Pearson Education, Inc., Permissions Department, One Lake Street, Upper Saddle River, New Jersey 07458, or you may fax your request to (201) 236-3290. ISBN-13: 978-0-13-705891-4 ISBN-10: 0-13-705891-8 Text printed in the United States on recycled paper at RR Donnelley in Crawfordsville, Indiana. First printing, June 2012 To Bob, Judy, Nancy, Laura, Steve, Bobby, Elizabeth, Julia, Gabriel, Michael, Moses, Delancey, and Harry. This page intentionally left blank Contents Preface Acknowledgments About the Author xxvii Part I Enabling Technologies, Data Centers, and VolP PBXs 1 Computing and Enabling Technologies Key Underlying Technologies Fiber-Optic Cabling: Underpinning High-Speed Networks 5 Faster, Lower-Priced Processors: Decreasing Memory Costs Sending Data in Packets Routing Efficiencies 8 Packet Contents: User Data ver