Lecture Notes: Session4/TDC 461

" Lines vs. Trunks, Centrex, PBX, and Key Systems; Voice Processing"


  1. Review:
    1. Using the conceptual telecommunications model, map the process of a live TV broadcast.
  2. Lines vs. Trunks
    1. Vocabulary
      1. Circuit=>
      2. Line=>
      3. Trunk=>
      4. Ports=>
      5. Blocking=>
      6. Non-Blocking=>
      7. Physical connection=>
      8. Logical connection=>




    Key Telephone System (KTS)

    Direct Inward Dial=>7-10 digit dial directly to desired person. No switchboard operator.

    Available; must be enabled and configured at the PBX for smooth operation.

    Inherently available

    Available only if a phone number has a single appearance within the system.

    Direct Outward Dial=>7=10 digit dial directly from desktop; no switchboard operator.

    Available; must be enabled and configured with proper routing, authentication, and tracking software.

    Inherently available

    Inherently available.

    Foreign Exchange (FX)=>

    Configured as a trunk.

    Configured as a trunk between Cos.

    Must occur through a Centrex connection. Configured as a trunk between Cos.

    Off-Premises Extension

    Configured as a telephone (line) rather than a trunk. Generally must be an analog line because of the number of A/D conversions required to achieve connectivity.

    Configured as a trunk between Cos.

    Must occur through the CO (Centrex), with same properties as Centrex OPX.

  3. Traffic Engineering
    1. Definitions and Goals
      1. Definitions=>
      2. Goals=>
    2. Where to get Information
    3. Accomplishing the Mission
    4. Using the Information
    5. Convert the data to Daily or Hourly Usage
    6. Choose the Appropriate Modeling Tool
      1. Poisson Distribution=>
        1. Point to Poisson demos on web page
        2. Poisson calculations use Centum Call Seconds rather than real seconds--basically dividing the traffic by 100.
      2. Erlang Distribution=>
  4. PBXs
    1. Overview and Review
      1. View of DePaul's Lincoln Park PBX
      2. View of Focal Communications humongous PBX and Switch
    2. Components of PBX system
      1. CPU
      2. Memory
      3. Stations (telephone sets)
      4. Trunks
      5. Switched network
      6. Cabinets
      7. Bus
      8. Console or switchboard
      9. Common logic
      10. Battery backup
      11. Wiring infrastructure
    3. Analog PBXs
    4. Digital PBXs
  5. Centrex
    1. Overview and Review
    2. Components
      1. CO
      2. CPU
      3. Station cards
      4. Switching Network
      5. Line cards
      6. Memory
      7. Common logic and power cards
      8. Bus
  6. Peripheral Devices (for all systems, not just Centrex)
    1. Automatic Call Distributors
    2. Automated Attendant
    3. Call Detail
    4. Least-Cost Routing
  7. Key Telephone Systems
    1. Overview and Review
    2. Components
      1. Key Service Unit (KSU)
      2. Line cards
      3. Station cards
      4. Intercom cards (optional)
      5. Telephone sets
      6. Power supplies and logic cards
      7. Wiring infrastructure
    3. Rationale for Key Systems
  8. Voice Processing
    1. Overview and Review
    2. Touch Tone and Voice Recognition
    3. Automated Attendant
    4. Automatic Call Distributors--5 main duties
      1. Prioritize calls
      2. Route the call to the appropriate agent
      3. Deliver any announcements, queue
      4. Direct busy calls to announcements
      5. Handle messages for call backs
    5. Voice Mail
    6. Interactive Voice Response