L10

INF 225: System Architecture and Networks

  • Faculty: Engineering, Built Environment and Information Technology, University of Pretoria

Voice and Data Delivery

  • Faculty: Engineering, Built Environment and Information Technology, University of Pretoria

Learning Outcomes and Objectives

  • Outcomes: Identify and explain the basic elements of a telephone system.

  • Objectives:

    • Identify fundamental components of a telephone system and discuss limitations of telephone signals.

    • Explain main characteristics of Asynchronous Transfer Mode (ATM) and its role in data transmission.

    • Describe the concept of convergence and its significance in modern communication technologies.

Outline

  • Basic Telephone Systems

  • PBX

  • DSL

  • Cable Modem

  • T1 Leased Line Services

  • Frame Relay

  • ATM

  • CTI & UC

Basic Telephone Systems

  • POTS: Plain Old Telephone System

    • Transmit voice at bandwidth < 4000 Hz

    • Requires two 4000 Hz channels for conversation

    • 4000 Hz analog signal: ~33,600 bps; digital signal: ~56,000 bps

  • Local Loop:

    • Connects central office to home/business; provides local dial tone

    • Long-distance calls handled by a long-distance provider

    • Local calls stay within Local Access Transport Areas (LATAs)

  • Trunk Lines:

    • Connect between central offices and other switching centers

    • Typically high-speed digital lines carrying multiple circuits

    • Telephone number consists of area code, exchange, and subscriber extension

PBX (Private Branch Exchange)

  • Internal phone switching for medium to large businesses

  • Provides advanced features (e.g., routing calls for lowest cost)

Automatic Call Distributor

  • Routes inbound calls in high-volume situations, such as customer service

Basic Telephone Systems Services

  • Foreign Exchange Service (FX): Connects local number to leased line remote site

  • Wide Area Telecommunications Service (WATS): Discounted volume calling

  • Off-Premises Extensions (OPX): Dial tone from a remote PBX

DSL (Digital Subscriber Line)

  • High data transfer rates over standard telephone lines

  • Speeds range from kilobits to megabits; distance limited to 5.5 km from central office

Cable Modems

  • Allow high-speed Internet access

  • Data transfer speeds: 500 kbps to 25 Mbps

T-1 Leased Line Service

  • Digital, synchronous TDM stream for businesses

  • Supports 24 simultaneous channels; provisioned for 1.544 Mbps

  • First introduced in 1962; can transmit multiple calls simultaneously

Frame Relay

  • Leased service offering high-speed connection between two points

ATM (Asynchronous Transfer Mode)

  • High-speed packet delivery service; capable of speeds up to 622 Mbps

  • Offers various classes of service

    • Constant Bit Rate (CBR): High-speed, continuous connection

    • Variable Bit Rate (VBR): Real-time applications

    • Available Bit Rate (ABR): Burst traffic

    • Unspecified Bit Rate (UBR): Lower rate traffic with potential delays

Computer-Telephony Integration (CTI)

  • Merges voice and computer networks

  • Offers features like unified messaging, interactive voice response, and third-party call control

MPLS and VPNs

  • Focus on security and speed when transmitting data over the Internet using MPLS labels and VPNs

Unified Communications

  • Integrates various communication forms (e.g., telephony, instant messaging) into one application

Conclusion

  • The end of presentation, University of Pretoria.