Date of Issue: 09-01-2023 Rate this Study Guide

Introduction to Telephony

by Annlee Hines

  Telephony networks came first.
    The price you pay for being a Monopoly
  All-analog to all-digital
    Recycling works in telephony, too
  People to people
Communication at a Distance
  An old problem
  Constraints on old methods
  "What hath God wrought?"
  "Mr. Watson, come here. I want you."
Voice Transport Starts with Voice.
  Voice characteristics
    Voiced sounds
    Unvoiced sounds
    Silence matters.
  Time is of the essence.
  Digitizing voice
    Frequency range
    Full duplex connections
    Advantages of digitizing voice
    How to measure call quality: MOS
Digitization and Compression
  Line coding
    Waveform coding
    Source coding
    Hybrid coding
  In-band vs. out-of-band
  SS7 Addressing
  Above Level 3
  Signaling at the end node
  Trunk Signaling
    Loop-start Signaling
    Wink-start Signaling
    Ground-start Signaling
  Voice and data signaling parallels
    Analog Telephony Equivalents to Layer 1 in Data Networks
Telephone Networks
  That annoying echo
    Statistical multiplexing
    Inverse multiplexing
  Numbering plans
  First time, every time
Packetizing Voice -- A Quick Look
  Voice ≠ Data
  Network similarities

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