The Birmingham Area Linux Users
About Asterisk
Asterisk is an open source Voice over Internet Protocol (VoIP) Public Branch Exchange (PBX) system that runs on Linux, Mac OS X, and even Windows (VMWare images are available).
Connectivity and Service Options
- POTS (Plain Old Telephone Service) - this is your standard Bellsouth telephone line
- T1/PRI multichannel digital service - unless you are fabulously wealthy this is likely only an option for businesses
- PSTN-VoIP provider - calls routed to/from PSTN over your broadband connection (DSL/Cable)
- VoIP-VoIP connectivity - supports direct VoIP calls over your broadband connection (DSL/Cable)
Features (some features require additional external programs/libraries outside of the base installation)
- Multiple phone extensions - can use it as an in-house intercom
- Multiple voicemail boxes
- Teleconferencing
- Ability to interface with custom programs - database lookups, web applications, weather, stocks, etc.
- Interactive Voice Response (IVR) - scripted menus to provide different options to your callers
- Text-to-Speech (TTS) - have Asterisk read your email to you
- Voice Recognition - control menus by voice rather than DTMF keypresses
- Email notification/attachment of voicemails
- Music on hold (MOH)
- Call Parking - transfer a call to a "parked" extension and then pick it up from any other extension
Client and Handset Options
- Dedicated VoIP handsets (wired or wireless)
- Softphones - telephone software to run on your PC, mobile device, etc.
- Standard analog POTS handset - requires an Analog Telephone Adapter (ATA or just TA) to convert the POTS signals to VoIP
For some reasonably interesting definition of the word "nifty", there are a lot of really cool things you could do with an Asterisk system. For example, say you're working away from home but would like to call friends or family who are "local" from your home installation. You could use a softphone to connect with your Asterisk system over the internet and configure a menu option that allows you to dial outbound from your "home" phone system and place that "local" call, all while you're sitting in an internet cafe halfway around the world.
Depending on the service plan you purchase, you can handle multiple inbound and outbound calls simultaneously. So even though I only have one Dial-In-Direct (DID) phone number we could have one person call into that number and ring my extension. Then a second caller could dial into that number and choose to ring my wife's extension. A 3rd caller dialing in and asking to speak to me could be routed directly to my voicemail (or even ignored) automatically based on their caller-id information. And at the same time my daughter could pick up a 3rd extension and place an outbound call.