Course 133
Fundamentals of VoIP & IP Telecom Networks

PART 1: THE BIG PICTURE

1. Introduction to Broadband Converged IP Telecommunications

We begin with a comprehensive big-picture introduction to today’s telecom network: the concepts of convergence and broadband, the different parts of the network, the three key technologies: Ethernet, IP and MPLS, what they are and what each does. You’ll learn how a service is implemented end-to-end, and identify today’s standard residential, business and wholesale services.

1. History of Telecommunications
2. Convergence
3. Broadband
4. Today's Telecom Network
5. Network Core
6. Ethernet, IP and MPLS
7. Network Access
8. Telecommunication Service Implementation
9. Carrier Interconnect
10. Residential, Business and Wholesale Services

2. Telecom Fundamentals

Next, we'll ensure you have a solid foundation in the fundamental ideas of telecom: the elements of a circuit; terminals, clients, servers and peers; how bits are represented on fiber with pulses; and how bits are represented with modems on wireless, cable TV and DSL. Then we'll understand how capacity is shared to carry many users' traffic on common facilities: Frequency Division Multiplexing, Time Division Multiplexing, overbooking and Bandwidth on Demand.

1. Communication Circuit Model
2. Terminals, Clients, Servers and Peers
3. Representing Bits on Digital Circuits: Pulses
4. Representing Bits in Frequency Channels: Modems
5. Serial and Parallel
6. Sharing: Frequency-Division Multiplexing
7. Sharing: Channelized Time-Division Multiplexing (TDM)
8. Efficient Sharing: Statistical Time Division Multiplexing
9. Overbooking and Bandwidth on Demand

3. Network Fundamentals

In this chapter, we'll ensure you also have a solid foundation in the fundamentals and jargon of the network. Today's converged telecom network is based on what used to be called "data communications": packets in frames. Without bogging down on details, we'll review basic circuit configurations, understand how routers relay packets from one circuit to another, and how the packets are actually transmitted from one device to another in frames. You'll fill gaps and get up to speed on IP packets, MAC frames and MPLS labels, what each is for and how they work together.

1. Data Links – Unbalanced: PONs, CATV, Wi-Fi, CAN-BUS
2. Data Links – Balanced: LANs and Ethernet
3. Frames & MAC Addresses
4. Networks
5. Packets, IP Addresses and Routers
6. IP Packets vs. MAC Frames
7. IP Packets
8. TCP, UDP and Port Numbers
9. MPLS Labels

4. The Internet, Cloud Computing, Data Centers and SD-WANs

The Internet, which started out as a way to send text email messages, is now worldwide converged broadband communications. In this chapter, we'll understand what exactly an Internet Service Provider does, and how they get packets delivered world-wide. We'll review web clients, browsers and apps, web servers, then understand the huge business of web services, cloud computing and data centers.

1. A Network to Survive Nuclear War
2. The Inter-Net Protocol
3. Internet Service Providers (ISPs)
4. Domain Name System (DNS)
5. Web Clients: Browsers and Apps
6. Web Servers: HTTP, HTTPS, HTML
7. Web Services
8. Cloud Computing and AWS
9. Data Centers
10. Internet IP VPNs
11. SD-WANs
12. Country-Spoofing VPN Service
13. Anonymizer VPN Service & The Dark Web

5. Digital Voice

The converged network carries all media: voice, video, text and images in packets. An essential first step is digitizing the media, representing it using 1s and 0s, to be carried in said packets. We'll understand how voice is digitized and reconstructed, and the G.711 64 kb/s standard, and other codecs.

1. Analog and Digital: What Do We Really Mean?
2. Continuous Signals, Discrete Signals
3. Voice Digitization (Analog → Digital Conversion)
4. Voice Reconstruction (Digital → Analog Conversion)
5. Digital Voice: 64kb/s G.711 Standard
6. Codecs and Voice Compression

PART 2: VoIP and SIP

6. VoIP Systems, Components, Standards, Jargon and Buzzwords

Next, we dive into the fundamentals of Voice over IP: the basics of communicating voice in IP packets, demystifying the jargon and buzzwords and explaining in plain English the components of a VoIP telephone system like soft switches and gateways, what each does, along with protocols like SIP.

1. The Big Picture
2. VoIP System Components
   1. VoIP Phones
   2. Voice in IP Packets
   3. Softswitches / SIP Servers / Call Managers
   4. Media Servers and Unified Messaging
   5. Gateways
   6. LANs and WANs
3. Key VoIP Standards
4. Where All of This is Headed: Broadband IP Dial Tone

7. VoIP for Individuals

"Voice over IP" can happen in many different ways. We'll review the many flavors of VoIP, comparing and contrasting the various implementations and architecture choices. Starting with Internet telephony, we will understand computer to computer VoIP over the Internet and different types of Internet - Public telephone network VoIP.  We'll cement your knowledge by tracing a VoIP phone call from a laptop in the classroom over Wi-Fi to the Internet, then to a mobile network operator and to a cellphone in the classroom, identifying all the circuits, components, buildings and companies involved in the end-to-end connection.

1. Internet Telephony: Computer-Computer VoIP over Internet
2. Internet Telephony Clients
3. VSPs: Internet to Phone e.g. Skype to Phone
4. Class Exercise: Trace a Phone Call from Laptop to Cellphone
5. VSP: Internet VoIP with Adapter and PSTN Phone Number e.g. Vonage
6. VoIP Becomes The New POTS

Class Exercise: Trace a VoIP Call End-to-End Internet to Cellphone
We'll establish a phone call from a VoIP client on a computer in the classroom via Wi-Fi and the Internet to a cellphone in the classroom, and identify where the voice packets travel, from one circuit, device, and company to the next, end-to-end between the two sets of microphones and speakers. This will cement your understanding of VoIP telephone calls, the telecom business and how everything is connected.

8. VoIP for Organizations

Next, we'll look at all the ways VoIP is implemented for organizations, including SIP Trunking to replace expensive PBX trunks. We will compare and contrast choices for a VoIP system: getting it from the phone company; buying a call manager / softswitch; renting a Hosted PBX; and cloud solutions. You'll gain the knowledge to confidently differentiate VoIP architectures and discuss pros and cons of options.  We'll complete the discussion with practical examples of VoIP in action.

1. VoIP-Enabled PBX and Migration Options
2. Premise Softswitch: PBX Replacement
3. Hosted PBX and Cloud Services: Softswitch as a Service (SaaS)
4. SIP Trunking
5. IP Centrex
6. Phone Powering and PoE
7. LAN Configuration for VoIP

9. Packetized Voice and Sound Quality

In this module, you’ll learn what exactly packetized voice is, how it happens, and the various standards in use. You’ll learn about the factors affecting sound quality, and how packets actually get “lost” in a network. We’ll listen to sound clips of impairments, and provide you with a practical checklist of tips and recommendations for ensuring success.

1. Voice Packetization
2. Measuring Voice Quality
3. Factors Affecting Voice Quality
4. Codecs and Compression
5. Delay
6. Jitter
7. RTP
8. VoIP Protocol Stack
9. RTP, UDP, IP, MAC
10. Packet Loss Mechanism
11. Packet Loss and Jitter Sound Samples
12. Testing and Troubleshooting Voice Quality: First Step: The IP Network
13. Testing and Troubleshooting Second Step: The VoIP

Class Activity: Sound Clips with Impairments
Listening to sound clips, you'll hear the effect of different levels of uncorrected delay, jitter and packet loss, and understand how the quality of the reproduced speech at the far end is affected.

10. SIP and Call Flow in the IP World

SIP is the open, standard protocol for setting up Voice over IP telephone calls. All VoIP systems that purport to be “compatible” or “standards-based” must implement the Session Initiation Protocol. SIP defines the procedure and messages to set up a phone call – or any other kind of communication. In this chapter, you’ll learn what exactly setting up a VoIP telephone call entails, understand what SIP is, how it works, demystify jargon like proxy server, registration and location server, understand how SIP fits in with softswitches and call managers, and trace the establishment of an IP phone call step by step. At the end of this, you’ll understand how VoIP phone calls are set up – maybe worth attending the course all by itself!

1. Softswitch vs. PBX or CO Switch
2. What SIP is and What it Can Do
3. Relationship to Other Protocols
4. SIP URIs: “Telephone Numbers”
5. Registration and Location
6. Outbound Proxy
7. Finding the Far End
8. The SIP Trapezoid
9. SIP Message Example
10. How SIP Relates to Softswitches and Call Managers
11. Relating PSTN Phone Numbers to SIP URIs

11. SIP Trunking and Carrier Connections

This chapter is all about connecting an in-building business VoIP phone system to the world. First, we’ll understand how connections used to be implemented with PBX trunks and ISDN PRI service. Then we’ll see how a gateway connects a modern VoIP system onto PBX trunks, and more importantly, how SIP Trunking replaces PBX trunks with a lower-cost and more flexible solution.

Many big organizations have an existing data network, implemented as a VPN by a carrier. We’ll look at the advantages and disadvantages of using the “data” VPN, or the Internet, compared to SIP Trunking, and finish off with a practical checklist of features and technologies to require when choosing a carrier.

1. Connecting with Gateways and Megaco
2. Class of Service (CoS)
3. SIP Trunking Service
4. VoIP at Carriers and Session Border Controllers
5. PSTN VoIP Interconnection at the Toll Center
6. PSTN Tandem Access Trunk Interconnection at the Toll Center
7. Comparing Transmission Choices

PART 3: NETWORKING

12. Organizing the Discussion

Much of the last day is devoted to understanding the modern IP-based telecom network. To get started, we’ll organize the discussion using the OSI 7-Layer Reference Model, explaining what a layer is, what the layers are, and giving examples of protocols like TCP and IP and where they fit.

1. Protocols and Standards
2. ISO OSI Reference Model
3. OSI 7-Layer Model
4. Physical Layer: 802.3, DSL, DOCSIS
5. Data Link Layer: 802 MAC
6. Network Layer: IP and MPLS
7. Transport Layer: TCP and UDP
8. Session Layer: POP, SIP, HTTP
9. Presentation Layer: ASCII, Encryption, Codecs
10. Application Layer: SMTP, HTML, English …
11. Protocol Stacks
12. Protocol Stack in Operation: Babushka Dolls
13. Standards Organizations

13. Ethernet, LANs and VLANs on Copper, Fiber and Wireless

Ethernet and its MAC frames are the building blocks of new telecom networks, both in-building and between buildings. A VoIP phone plugs into a copper Ethernet LAN cable, or uses an Ethernet Wireless LAN to connect to the network. The network itself is built with point-to-point circuits conforming to the Optical Ethernet standard connecting equipment in different locations with fiber.

In this module, you will learn the basic principles of Ethernet and LANs, the crucial concepts of MAC addresses, MAC frames and broadcast domains, how devices connect via LAN switches, and how VLANs separate groups of users.

1. MAC Addresses, MAC Frames and Broadcast Domains
2. Ethernet and 802 standards
3. LAN Switches, a.k.a. Layer 2 Switches
4. VLANs
5. Optical Ethernet
6. Wireless Ethernet (Wi-Fi)

14. IP Networks, Routers and Addresses

Routers implement the network by relaying packets from one circuit to another. Determining which circuit to relay the packet to is the routing part of the story. In this module, you will fill in gaps, learn how IPv4 addresses are organized and how they are used to route packets between telephones during a VoIP phone call. We’ll cover DHCP, static vs. dynamic addresses, public vs. private addresses and NAT. To be ready for the future, we’ll finish with a review of the IPv6 address structure and usage.

1. IPv4 Address Classes
2. Subnets
3. DHCP, Static and Dynamic Addresses
4. Assigning Subnets to Broadcast Domains
5. IP Network: Routers Connected with Dedicated Lines
6. Routers and Customer Edge
7. Public and Private IPv4 Addresses
8. Network Address Translation
9. IPv6
10. IPv6 Address Allocation and Address Types

Class Exercise: IP and MAC Addresses
Using the Windows interface, we'll determine the current MAC and IP Addresses of a classroom computer, and the private and public IP addresses of the Edge Router and NAT it's connected to. This will help visualize what IP addresses are, and covers two of the questions on the Final Exam.

15. MPLS and Carrier Networks

The Internet does not come with any performance guarantees for end-users: when the next packet will be transmitted, and how often that might happen… but banks, carriers, government and large organizations need to have written guarantees. Guaranteed IP packet data communications between locations is called an MPLS VPN or MPLS service. We’ll demystify and sort out VPN, Quality of Service, Class of Service (CoS), Service Level Agreement (SLA) and see how MPLS is used.

1. Carrier Packet Network Basics
2. Service Level Agreements
3. Provider Equipment at the Customer Premise
4. Virtual Circuit Technologies
5. MPLS
6. MPLS VPN Service for Business Customers
7. MPLS and Diff-Serv to Support Classes of Service
8. MPLS for Service Integration
9. MPLS for Traffic Aggregation