Asterisk

1
Asterisk

• The Open Source PBX Telephony Platform

2
Topics

• Basic Telephony terms
• VOIP Protocols (relevant ones)
• Asterisk info
• How to control and change settings
• Configuration files
• Live demo
• Set up your soft phone
• Set up Grandstream SIP Phone

3
Terms

• PBX - Private Branch Exchange
• The control center for a phone system
• Also called a switch or switchboard
• PSTN - Public Switched Telephone Network
• POTS - Plain Old Telephone System
• Uses 48 VDC for passing analog voice
• Rings at around 90-100 VAC

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Terms

• DTMF - Dual Tone Multi Frequency
• Tones used to dial and send signals to the switch
• Inband
• Uses same frequencies we talk with
• Some peoples voices can trigger this (mostly
  females)
• rfc2833
• Out of band standard for passing dialing tones

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Terms

• FXS - term used with POTS for a system that
  supplies voltage for dial tone and ring voltage
• FXO - term used with POTS that connects to an FXS
  system. Your telephone is FXO.
• (These are mixed up a lot)

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Terms

• Softphone - software phone that runs on your
  computer
• Hardphone - Hardware phone
• VOIP - Voice Over the Internet Protocol
• Generic Term for all IP telephony
• Skype
• Ventrilo
• Teamspeak
• As far as I know always uses UDP/IP. Can use
  TCP/IP but why?

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Terms - Protocols

• SIP - Session Initiation Protocol
• Used to set up the VOIP call
• Only sets up the connection
• Passes voice packets off to RTP
• RTP - Real-time Transport Protocol
• Carries the voice packets for a SIP phone call
• Issues with NAT (uses different ports than SIP)

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Terms - Protocols

• IAX - Intra Asterisk Exchange
• Designed by Asterisk
• Uses same port for both connection and voice
  packets so better through NAT
• DUNDi - Distributed Universal Number Discovery
• Just put in here because sample .conf files have
  code for it.
• New protocol NOT universaly used but supported by
  Asterisk

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The Last Mile

• The last mile is the term used to describe how
  the telephone company gets the signal to your
  home or office.
• Typically POTS
• Ironic as they convert everything to digital from
  that point and send it down the trunk.

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Asterisk

• Open Source (nix only, but windows bransh
  avalable)
• Current Version 1.4.21.2
• Version 1.6 RC6 is out
• Code base controlled by Digium Inc.
• Can run on a headless system
• Business model is give away the software and sell
  the hardware.

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Asterisk Control

• Command line and .conf files
• /etc/asterisk except zaptell.conf which is in
  /etc
• More on .conf files later
• If you like emacs, vi or the like enjoy
• You need to know the Asterisk syntax and settings
• There are alternatives..

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Asterisk Control

• GUI tools
• Asterisk GUI
• Web based AJAX
• Edits .conf files directly
• Same UI as AsteriskNOW (more later)
• Says can edit .conf files manualy or use GUI and
  will not have problems (WRONG)
• Does not use Apache, has own web server
• /etc/asterisk/http.conf holds settings

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Other Free PBXs

• OpenPBX by VMX
• Not the same as CallWeaver
• CallWeaver - formerly OpenPBX.org

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Asterisk Control

• GUI Tools (cont)
• AsteriskNOW
• From Digium
• Self installing with OS, Asterisk, and GUI
• Wipes out ALL hard drives on the machine
• Trixbox
• Similar to AsteriskNOW but has better UI

15
Configuration Files

• Only going to mention the most used
• extensions.conf
• Sip.conf
• Iax.conf
• Users.conf
• Manager.conf
• Logger.conf
• Voicemail.conf
• Asterisk.conf
• Manager.conf
• Zaptel.conf

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Configuration Files

• extensions.conf
• Holds the Dial Plan
• Most complex to set up
• Context
• incoming
• Code here
• general
• Has some settings
• globals
• Holds global variable info

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Configuration Files

• extensions.conf (cont)
• Funky syntax
• exten gt (extension) a unique series of steps
• exten gt extension, series number, application
• Exten gt 123, 1, Answer()
• exten gt 123, n, Wait(2)
• exten gt 123, n, Background(tt-weasles)
• exten gt 123, n, Hangup()

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Configuration Files

• extensions.conf (cont)
• Include
• Include name of another context
• Include default
• Macros
• Used to create reusable code
• Can accept paramaters

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Configuration Files

• asterisk.conf
• Tell Asterisk where thing are located
• Log files
• Run directory
• Set verbosity of console
• Turn debug on
• System limits (max calls)

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Configuration Files

• features.conf
• Mostly for parked calls settings
• http.conf
• Setting for the Asterisk GUI web server
• rtp.conf
• Limit the ports RTP can use

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Configuration Files

• iax.conf and sip.conf
• Settings for connections
• sip.conf for sip connections, ias.conf well you
  get it
• Not used with GUIs, users.conf holds all that
  data
• Contexts like in extensions.conf
• 101 will be phone extension 101
• All settings for that user under that context

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Configuration Files

• zaptel.conf
• Used to set up hardware for connecting your
  Asterisk system to POTS, either in or out.
• I did not use this so cant help here

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• manager.conf
• Settings for the Asterisk GUI
• Turn it on or off
• Timeout
• Password and user
• Amount of control the GUI has

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Configuration Files

• logger.conf
• Name of log files
• What to log
• voicemail.conf
• Turn on voicemail for a user
• What capabilities the user has in VM

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Configuration Files

• users.conf
• Combines most of iax.conf, sip.conf, zaptel.conf,
  and voicemail.conf into one file.
• Changed in later releases to make management
  easier
• Uses contexts again like in sip.conf and iax.conf
• Will show an example later

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Phones

• Hardphones
• Grandstream BT200 inexpensive (about 50)
• Only has 7 segment display so not caller ID name
  only number
• Having problems with staying connected to
  Asterisk
• Set up TFTP to set up firmware and ring tones for
  the phones
• Use SIP
• 100bTx in and out
• Grandstream HT503
• Multi use device
• FXO to FXS
• FXO to SIP
• FXS to SIP
• FXS to FXO
• One 100bTx in and out

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Phones

• Soft phones - program that runs on a computer
• Xlite SIP (my favorite)
• Zoiper - IAX

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Resources

• Asterisk, The Future of Telephone, 2nd ed.
• OReily Publishing
• Free PDF download from asterisk.org
• Keep in mine this book does not talk about
  users.conf
• voip-info.org
• asterisk.org
• trixbox.org
• asterisktutorials.com
• I found a web site from a San Diego company that
  had great Trixbox tutorials but alas I cant find
  it now.