Redial: Interactive Telephony

Shawn Van Every
Spring 2009
Wednesday 12:30 to 3:00 PM H79.2574.1

Important Resources:

Syllabus (this page):
ITP Telephony Listserv: Subscribe
Class Wiki:


Office Hours:

Tuesdays 1PM to 2:30PM and Wednesdays 4PM to 5:30PM


20% Assignments
25% Class Participation/Attendance
25% Final Project
15% Midterm
15% Presentation


Mandatory, unexcused absences will affect your final grade. If you are going to be absent, please let me know ahead of time if you can.


Excessive lateness will affect your grade. Don't be late.


Laptop use is prohibited while other students are presenting or during discussion. While I am lecturing you may use them for note taking or class related work. In other words, respect your fellow students and don't check your email.



Asterisk The Future of Telephony, Second Edition - O'Reilly - Jim Van Meggelen, Jared Smith and Leif Madsen
(Published under Creative Commons and available online at:
Wired for Speech - How Voice Activates and Advances the Human-Computer Relationship - Clifford Nass and Scott Brave


Asterisk Documentation Project (seems to be down)
VoIP Watch
VoIP & Gadgets Blog


This class will have weekly homework assignments, readings along with a midterm and final project. All are required. Failure to do assignments or participate in class discussion on readings will adversely affect your grade. Assignments will be posted on syllabus each week. Please check syllabus for current assignment even if they aren't mentioned in class.


VoIP and Internet Telephony are fast moving areas. Telephony in general has a long history and has had dramatic effect on culture and society around the world. Unfortunately, 14 weeks is not enough time to cover all of the emerging technical aspects nor the rich cultural and societal impact that telephony has had. In order to add more variety into the course material each student will be assigned to a group to give a short (15 minutes maximum) presentation on one historical, cultural, societal or emerging technical aspect that we are not covering in course material.

Weekly Rundown:

Week 1

Introductions: Syllabus, Examples, VoIP basics and Asterisk
  • Find some interesting examples of using the phone for performance, information retrieval, social purposes and so on. Add them to the class wiki and prepare to dial or otherwise show/talk about in class.
  • Get up and running with your Asterisk account. Try some simple commands in your Dialplan such as SayDigits, Playtones, Playback, and so on. Use the Asterisk book or as a reference.
  • Reading:
  • Chapters 1 and 5 (Ignore "Using the Dial() Application") of Asterisk: The Future of Telephony

  • Week 2

    Asterisk 101: Voicemail, Manager Interface, Basic Unix and more with the Dialplan
  • Try out the Asterisk Voicemail System
  • Using the Dialplan, build your own Voicemail System that solves issues that you think voicemail has
  • Reading:
  • Chapters 5 (again) and 6 in Asterisk book
  • VoIP Hacks Handout

  • Week 3

    Softphones and Dialplan (Continued): Advanced Commands
  • Setup a softphone for your use with Asterisk
  • Try out the "Dial" application both through the Dialplan and with "call files". (Be responsible)

  • Week 4

    Programming Asterisk: PHP 101, AGI Scripting
  • Get familiar with PHP programming and try some simple AGI scripting
  • One idea might be to write an AGI script that reads the time and temperature

  • Week 5

    Programming Asterisk Continued
    Bridging to the Web
  • Come up with a midterm project idea. Describe the project in a blog entry or web page. Give some background (why you want to do the project) as well as a development plan. Look for potential collaborators.
  • Start midterm development

  • Week 6

    Midterm Workshop and Review

    Week 7

    Show Midterms

    Week 8

    Controlling Devices by Phone (by Network)
  • Reading: Chapters 1 through 4 in Wired for Speech
  • Keep going with projects you are working on!!!

  • Week 9

    Using Phones to Control Displays (with Processing and Flash)
  • Build a tic-tac-toe game using either a network object or Flash/Processing and a phone

  • Week 10

    Speech Synthesis (Festival)
    Speech Recognition (Sphinx/Lumenvox)
  • Final Project Ideas: Prepare to pitch to class

  • Week 11

    Final Project Proposals
    Additional Topics

    Week 12

    Final Project Workshop 1
    Additional Topics

    Week 13

    Final Project Workshop 2
    Additional Topics

    Week 14

    Let's See it! Show final projects, Expect guests

    Additional Topics (depending on time):

  • Phreaking
  • VoiceXML
  • iChat/AIM/Skype/GTalk/Yahoo Messenger and the like
  • Emerging VoIP Topics: Presence, Web 2.0 APIs and whatever else comes up
  • SIP to SIP dialing and IP only phone networks (Free World Dialup, ENUM)
  • Basic Telephone Electronics
  • Asterisk GUIs
  • Streaming from Phone