Introduction to Telecommunications Introduction to Telecommunications Contents. Preface... xvii

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1 Introduction to Telecommunications Contents Preface... xvii Prerequisites...xvii Who Should Study This Course?...xvii Key Topics...xviii Course Objectives...xviii How Do I Use This Course?...xix Real-World Scenarios...xix Pedagogy...xix Key Terms...xix Resources Available in Instructor-Led Settings...xix Why Choose WestNet?...xx Introduction... xxi Course Overview...xxi Module 1 The Public Switched Telephone Network...1 Lesson 1 Telecommunications History...12 Invention of the Telephone : American Telephone and Telegraph : Initial Competition : Government-Approved Consolidation : Federal and State Regulation : The Hush-a-Phone Decision : The Consent Decree : Carterfone Decision : Competition From MCI : Breakup and Divestiture...17 Regional Bell Operating Companies...18 Local Access and Transport Areas : More Freedom for the RBOCs...19 iii

2 1996: Telecommunications Act...19 Long Distance Service From RBOCs...19 Local Service From Interexchange Carriers (IXCs)...20 Interconnection...20 Cross-Region Competition...20 Manufacturing : New Rules for Unbundling Network Elements...21 Lesson 2 Elements of the Telecommunications Business...25 The Players...25 Interexchange Carriers...26 RBOCs/Local Exchange Carriers...26 Competitive Local Exchange Carriers...26 Competitive Access Providers...27 Regulated Competition...28 An Expanded Role for the FCC...28 Local Number Portability...29 Shared Platforms...29 Network Interconnection...29 Unbundled Local Loops...29 Reciprocal Compensation...30 Tariffs...30 Effects of Competition...30 Legal Struggles...30 Price Pressure...31 Slamming...31 Lesson 3 Local Exchange Components...34 The Telephone System Hierarchy...35 Class 5 Central Office: The Local Exchange...37 Class 4 Central Office...39 Tandem Central Offices...41 Class 1 Offices...42 Class 5 Central Office Components...43 Switching and Routing...43 Semipermanent Circuit Connections...44 IXC Point of Presence...45 Billing...45 Customer Premises...45 Local Exchange Calling Options...46 Local Exchange Carrier Does It All...46 Competitive Local Exchange Carrier Serves as Reseller CLECs Switch and ILECs Wire...46 CLEC Does It All...47 iv

3 Contents Lesson 4 Central Office Switching...50 The Talking Path...50 Evolution of Telephone Switching...52 Step-by-Step Switching and Rotary Dial Telephones...55 Crossbar Switching...57 Later Electromechanical Switching...58 Digital Switches...59 DTMF Signaling...59 How a Call is Made...61 Dial Tone...61 Entering a Telephone Number...61 Call Routing...61 Ringing...64 Ending the Call...65 Long Distance Voice Routing...65 Signaling...66 In-Band vs. Out-of-Band Signaling...66 Signaling System Telephone Numbering System...67 The Dwindling Supply of Numbers...68 Local Number Portability...69 Assigning Telephone Numbers...71 Special Area Codes...71 Special NXX Codes...71 Special Information: Hearing-Impaired Services: Service Codes, or N11 Numbers...71 Toll-Free: 800, 888, 877, etc Premium: Services...73 Follow-Me: Lesson 5 Trunks, Lines, and Loops...76 Telecommunications Terms...77 Loops...78 Lines...78 Trunks...79 Trunk Direction...80 Trunk Capacity...80 Trunk Transmission Type...80 Analog Transmission...80 Analog Bandwidth...82 Digital Transmission...82 Digital Bandwidth...83 Channels and Multiplexing...84 Multiplexing...84 v

4 Pulse Code Modulation (PCM)...86 Types of Trunks...89 Special Access Trunks...90 Tie Trunk...90 Private Lines...91 Foreign Exchange...91 Ring Down...93 Trunk Pricing...93 Lesson 6 Outside Wire Plant...96 Transmission Media...97 Copper...97 Twisted Pair...98 Twisted Pair Cable Color Codes Coaxial Cable Fiber Optic Cable Wireless Transmission Microwave Geosynchronous Satellites Low Earth Orbit Satellites Cellular Phones Comparing the Media Media Convergence Summary Quiz Module 2 Customer Premise Equipment Lesson 1 Key Systems Key System Components Cordless Key Systems Limitations of Key Systems Hybrid Systems Lesson 2 Central Office Exchange Centrex Centrex Benefits Technical Requirements for Centrex Distance From CO Switch Allocation of Call Paths Customer Premises Equipment IP Centrex Features IP Centrex Centrex vs. PBX vi

5 Contents Lesson 3 Private Branch Exchange PBX Components Trunks Extension Lines Equipment Cabinet Telephones and Attendant Console Administrative Terminal Making a Call on a PBX Calling on an IP PBX Call Routing Supplementary PBX Features Direct Inward Dialing Direct Inward System Access Uniform Dialing Plan Station Set Features Attendant Console Services Call Accounting Authorization Codes Account Codes Administration and Management Reports Call Detail Reports Test Reports Busy-Hour Studies PBX Enhancements Voice Response Voice Recognition Call Following Automatic Call Distributor Other Auxiliary Equipment Paging Equipment Call Management System PBX Costs and Requirements Lesson 4 Voice Mail Systems Voice Mail Features Voice Mail/PBX Integration Design Factors Unified Messaging Broadcasting Voice Mail Security Automated Attendants Lesson 5 Systems Installation Considerations System Power Considerations DC Power AC Power vii

6 viii System Grounding The National Electric Code Reasons for Grounding Overvoltage Protection Voltage Stabilization Provide a Path for Overcurrent Devices Approved Grounds Multiple Approved Grounds Ground Reference Points Line Power Conductor Identification System Environmental Concerns Heat Dissipation Temperature and Humidity Air Purity RFI Noise ESD Summary Quiz Module 3 Telephony Services Lesson 1 Analog Voice Services Voice Billing Options Flat Rate Measured Service Local Measured Service Mileage-Sensitive Rates Enhanced Voice Services Call Waiting Call Forwarding Conferencing Call Hold Voice Mail Speed Calling Distinctive Ringing Call Pickup Hunting Custom Local Area Signaling Services Caller ID Anonymous Call Blocking Continuous Redial Callback Call Rejection Priority Call Preferred Interexchange Carrier Call Trace...207

7 Contents Operator Assistance Directory Listings Package Deals Internet Call Waiting Lesson 2 Signaling Basics Supervisory Signals Loop Start Ground Start E&M Emulated Tie Trunks Wink Start Digital Signaling Address Signals Dial Pulse Signaling Dual Tone Multifrequency Signaling Alerting Signals Control Signals In-Band vs. Out-of-Band Signaling Lesson 3 Digital Line Services The Significance of Digital Communications T1 Lines T1 Bandwidth The Digital Signal Hierarchy Digital Voice Transmission Digital Data Transmission Subscriber Line Carrier Integrated Services Digital Network How ISDN Works Basic Rate Interface Primary Rate Interface Channel Bonding and Non-Facility Associated Signaling Digital Transmission Methods ISDN Voice Features Required Hardware NT1: Network Termination, Type NT2: Network Termination, Type TA: Terminal Adapter TE1, TE2: Terminal Equipment, Types 1 and R, S, T, and U Interfaces Synchronous Optical Network How SONET Rings Work Digital Subscriber Line ix

8 x Lesson 4 Connecting to the Internet The Internet Hierarchy Tier Tier Autonomous Systems Network Access Points How the Hierarchy Works Internet Service Providers Single-User Dial-Up Access Connecting a Business to an ISP Non-Dedicated Access Dedicated Access Components of a Dedicated Connection Common Carrier Connection Channel Service Unit/Data Service Unit Broadband Modem Router Getting an Internet Address Summary Quiz Module 4 Internet Telephony Lesson 1 The TCP/IP Protocol Suite TCP/IP Protocol Layers and the OSI Model The OSI Stack The TCP/IP Model Layers Network Interface Layer Protocols Internetwork Layer Protocols Transport Layer Protocols Application Layer Protocols Communication Using TCP/IP Application Layer Transport Layer Network Layer Network Interface Layer Destination Station Lesson 2 IP, UDP, and TCP Overview of IP Best-Effort Service Multiplexing Protocols IP Packet Encapsulation IP Addresses...286

9 Contents Class A Address Class B Address Class C Address Class D Address Class E Address Dotted Decimal Notation Getting an IP Network Address Public Networks Private Networks UDP and TCP Demultiplexing Based on Port Number Types of Port Numbers Well-Known Port Numbers Ports and Addressing Lesson 3 Packet Telephony How Packet Telephony Works Packet Telephony Standards Packet Telephony Architectures IP Trunks Between Sites IP Trunks and Telephones Call Processing on IP Telephones and Trunks LAN-Based PBX Systems Internet VoIP Service Summary Quiz Module 5 Convergence and VoIP Lesson 1 Overview of Telecommunications Standards ITU-T Protocols Commercial Telecom Standards Codecs Multimedia Call Control and Signaling H.32x Multimedia over Data Networks Call Setup, Signaling, and Control Protocols Supplementary Packet Telephony Services ISDN Protocols ISDN Switching and Signaling Protocols Terminal Protocols Data Communications Over the Voice Network Packet Data Network Protocols IEEE ANSI Telcordia xi

10 EIA and TIA IETF RFCs Internet Standards BCP Lesson 2 General QoS Concepts Network Requirements for Convergence Converged Network Architecture A Hybrid Approach to Convergence Parallel WAN Paths for QoS Application-Level QoS Voice Quality The QoS Parameters Bandwidth Throughput Delay Encoding, Decoding, and Compression Packetization Jitter Jitter Buffers Measuring Jitter Wander Packet Loss Availability Security Lesson 3 Admission Control and Traffic Shaping Admission Control Traffic Shaping Traffic Smoothing Traffic Burst Shaping Network Admission Policies Admission Control and Traffic Shaping Applications Lesson 4 Traffic Prioritization Q VLAN Standard The VLAN Tag Q as an Architecture Q Protocols p Traffic Prioritization Standard Priority Tags and Traffic Classes How 802.1p Prioritizes Traffic Mapping 802.1p Traffic Prioritization to IP and ATM Networks. 364 xii

11 Contents Lesson 5 H.323 Standard for Packet Multimedia Overview of the H.323 Standard Version 1: Videophone Version 2: Packet-Based Multimedia Version 3: Under Development Other Standards of the H.323 Family Fundamental H.323 Network Components Terminals MCUs Gateways Gatekeepers MGCP MGCP Network Components MG MGC The H.323 Protocols and Their Effect on Voice Stream QoS H.323 Protocols Audio Codecs Silence Suppression G.711 Companding Algorithms MOS Audio Codec Delays DSPs DSP Delays RTP Time Stamping Sequencing ertcp RAS: H Call Signaling: H Control Signaling: H H.323 Protocol Limitations Document Conferencing: T.120 Series Integration with the Digital PSTN ISDN/VoIP Integration Adding SS7 to VoIP Network Infrastructure Requirements Lesson 6 H.323 Call Processing H.323 Call Progression Phases Gatekeeper Discovery and Registration: H.225 RAS Call Setup and Signaling: H Control Signaling: H Call Termination: H.245/H H.323v2 faststart SIP SS7 to ITSP Call Progression xiii

12 xiv Lesson 7 Session Initiation Protocol SIP SIP Messages Request Messages SIP Addresses Request Message Format Response Messages Response Message Format SIP Servers Proxy Redirect Registrar SIP Clients SDP Creating a SIP Session Lesson 8 Approaches to IP Network QoS IP Header Features ToS Field IP Precedence DiffServ DSCP Code Points PHB Standard PHBs Custom PHBs DiffServ Domains IntServ RSVP CBQ COPS MPLS Policy Routing PQ RED Traffic Shaping WFQ WRED Lesson 9 CO Softswitches What is a Softswitch? Softswitches in Telecomm Leveraging Legacy Networks Who is Using Softswitches? Local Voice Switching Toll Bypass Features and Benefits of Softswitch Systems...437

13 Contents Summary Quiz Course Quiz Glossary Index xv