A Gentle Introduction to Asterisk:
Taking Back Your Phone

Sean Reifschneider

Other Alternatives

• Trixbox http://www.trixbox.com/
• OpenPBX.org http://www.openpbx.org/
  • Forked from Asterisk 1.2
• YATE http://yate.null.ro/pmwiki/
• FreeSwitch http://www.freeswitch.org/
• Bayonne (IVR-only): http://www.gnu.org/software/bayonne/
• SipX http://www.sipfoundry.org/sipX
• Live CDs: http://www.voip-info.org/wiki-Asterisk+Bootable+CDROM

Example uses:

• "If you are a telemarketer, put this number on your do not call list and hang up, otherwise press 1 to speak to Sean or 2 to speak to Evelyn."
• Answering machine with web interface and e-mailed messages.
• Auto-attendant
• Conference call bridge
• If Bob calls, try the home phone then my cell phone then voicemail.
• Cell phone voice mail to e-mail.
• Run scripts from phone calls.
• E-mail notification of voicemail.
• Free calls over the Internet.

What is an Asterisk System?

• Connection to the phone system.
  • FXO POTS, VoIP, PRI, T1.
• Connection to extensions.
  • FXS POTS, SIP hard or soft phones, Bluetooth.
• Routing calls between the above.
  • Attendant, extensions, time-based, DID.
• Applications
  • Voicemail, music on hold, call forwarding, conference...
• http://www.asterisk.org/support/features

Phone system connections

• Another PBX (IAX, SIP)
• FXO POTS (Digium X100, $30 on ebay)
  • A very special modem card.
• A VoIP provider (particularly IAX)
  • We use nestegg.com, contact me for details.
• ISDN BRI/PRI
• Channelized T1/E1
• Digium TDM410 4-port ($550+)
• Xorcom USB channelbank 8-port ($850+)

Extensions: Hard phones

• Normal POTS phones.
• Via: ATA, TDM410, IAXy
• Digium TDM410 4-port ($550+)
• Xorcom...
• VoIP phone ($50-$150+)

Extensions: Soft phones

• Turns your computer into a cell phone
• Many protocols (SIP, IAX, Skype)
• kiax, kphone, gnophone, twinkle, shtoom, linphone, cornfed...

Configuration: Home Starter

• Answering machine.
• Cost: $30

Configuration: Home Next Step

• FXO and FXS
• Intercept calls.
• One external line, one internal.
• Cost: $100

Configuration: NAT/Gateway

• Internal phones (POTS or SIP)
• Asterisk
• External line(s) (POTS or SIP)
• Star wiring or Ethernet
• Digium 4-port PCI card with FXO/FXS modules?
• Cost: $300-$700

Video calls:

• I know nothing!

Gotchas:

• Configuration can be subtle and quick to anger.
• Test your changes.
• Cheap cards are worth their weight in crap.
• Sometimes I've had weirdness with calls not going through.
• Usually pretty reliable