.4 Capacity Restrictions on the Loop 2.4.1 What is Speech? 2.4.2 The Voiceband 2.4.3 Bandwidth 2.5 Problems with Analog Transmission 2.5.1 Attenuation and Amplifiers 2.5.2 Noise 2.6 Plain Ordinary Telephone Service 2.6.1 Twisted Pair 2.6.2 Components of a Telephone 2.6.3 Supervision 2.6.4 Call Progress Tones 2.7 Network Addresses: Telephone Numbers 2.7.1 Area Codes 2.7.2 Pulse Signaling 2.7.3 DTMF Address Signaling 2.8 SS7: Signaling System 7 2.8.1 Advanced Intelligent Network (AIN) 2.8.2 AIN Services 2.9 Summary 3 TELECOM EQUIPMENT We'll round out our discussion of telephony with a practical overview of different types of equipment that can be connected to the telephone network. Without bogging down on details, we'll sort out switches, PBXs, ACDs, IVRs, Call Centers and modems, including a discussion of DSL and how it is provided. 3.1 Telephone Switches 3.1.1 PBXs 3.1.2 Centrex 3.2 Computer-Telephony Integration 3.2.1 Voice Mail 3.2.2 IVR: Interactive Voice Response System 3.2.3 ACD: Automated Call Distributor 3.2.4 Inbound Call Centers 3.3 Modems and DSLAMs 3.3.1 Voiceband Modems 3.3.2 Bits per Hertz? 3.3.3 DSL: "Digital Subscriber Lines" 3.3.4 DSL Equipment 4 THE TELECOMMUNICATIONS INDUSTRY A practical overview of the telecommunications industry: service providers and alliances, competitive forces, structure and regulation; resellers, IXCs, LECs and CLECs. 4.1 US Domestic Telcos 4.1.1 LECs and LATAs: Local Exchange Carriers 4.1.2 IXCs: Inter-Exchange Carriers 4.1.3 Resellers 4.1.4 Consolidation 4.2 Canadian Telephone Companies 4.3 Trunks and Switching Centers PAGE 5 TELECOM 101 REFERENCE BOOK TERACOM TRAINING INSTITUTE 4.4 Network Access for Long-Distance 4.4.1 POP: Point of Presence 4.4.2 Equal Access 4.5 CLECs: Competitive Local Exchange Carriers 4.5.1 DSL from CLECs 4.5.2 Voice over DSL 5 DIGITAL COMMUNICATIONS This chapter will give you a real understanding of what "digital" means, and how it is implemented. We'll explain what a "DSO" is, and take a practical tour of digital circuits, including T1, T3, SON