[NMLUG] Fun with Asterisk

[matt at mattorama.net (Matt Grommes)]

Make sure you try Asterisk@Home as well. It's a bootable CD that auto-installs Linux and a ton of 
Asterisk stuff for you. It includes a couple of web-based tools to configure everything as well.

Here's a good howto for A@H: http://mundy.org/blog/index.php?p=87
That site has a bunch of cool tutorials on doing fancy stuff with Asterisk.


MATTHEW BOWIE wrote:
> Hi everyone,
> 
>  I've been playing w/ Asterisk lately and I thought I'd post my 
> experiences for those of you who haven't worked with it, and to see if 
> any of you have had any experiences with it you would like to share.
> 
>  The whole thing started when a vendor wanted to sell us VoIP services.  
> For our ~110 phones, they want to charge around $70K for 
> hardware/software/phones.  Our current provider charges around $20K a 
> year for leasing equipment/phones, so the $70K for purchase wasn't too 
> rediculous.  In preparation for their presentation I figured I'd bone up 
> on my VoIP and install a test Asterisk server.
> 
>  For those of you who are not familiar w/ Asterisk, it is an open source 
> PBX.  PBX stands for Private Branch eXchange.  It's basically the 
> hardware or software that routes calls in an office.  It's a smaller 
> version of the system the phone company uses to route calls.
> 
>  Ok, so I started w/ my favorite distro, Gentoo, and emerged Asterisk.  
> While it was compiling I looked for a decent softphone (software phone) 
> for Linux and Windows.  I decided to use a SIP (Session Initiation 
> Protocol) phone instead of one that supports IAX (Inter Asterisk 
> eXchange) because most IP hardphones you can buy use SIP, so I wanted to 
> make sure that portion worked well.  I finally ended up w/ Twinkle for 
> Linux and either SJPhone or XLite for Windows.  I may end up writing a 
> custom softphone if we put the system into production.
> 
>  Ok, so Asterisk finishes installing, and I have Twinkle installed on my 
> laptop and SJPhone installed on my assistant's WinXP machine.  One thing 
> that should be noted is that running a SIP softphone on the same machine 
> as Asterisk doesn't work (at least out of the box).  So I add two 
> entries to /etc/asterisk/sip.conf, assigning usernames/passwords.  Then 
> I add assign extenstions (123 and 125) to 
> /etc/asterisk/extensions.conf.  Ok, time for a test.  Log on to 
> softphone on my laptop (123) and dial 125.  WinXP machine starts 
> ringing.  Assistant picks it up, and just like that we're talking.  Ok, 
> basic phone to phone works.  Now for fun stuff.
> 
>  I add voice mail accounts for each extensions.  Then I install Festival 
> (text to speech engine) and create another extenstion, that when called 
> just has festival read out some random text.  Festival doesn't sound 
> great, but it's understandable, and since it's not recorded, we can use 
> it for dynamic stuff.  I test out call parking.  Everything seems to 
> work ok.
> 
>  Ok, the really cool thing about Asterisk is the ability to interface 
> with it from other programs.  To have Asterisk make calls and connect to 
> extension, you can simply move a .call file into it's spool directory.  
> This means any cron job, bash script, or program in any language can 
> initiate calls.  There's also the Manager system which will allow to 
> connect and control asterisk via TCP.  It can make calls, transfer 
> calls, keep your program notified of activity, etc.  Asterisk can also 
> call programs (which communicate w/ Asterisk using stdin and stdout).
> 
>  So what's all this good for?  Ok, let's look at outgoing calls.  If 
> students haven't made payment arrangements by a certain date, they are 
> disenrolled from classes.  Every semester there is usually over a 
> hundred students on the purge list.  Two days before purge, we could run 
> a script that would query the database, find everyone who is going to be 
> purged, get their phone number, connect to their phone and when answered 
> play a recording letting them know they will be disenrolled unless they 
> make arrangements.  If it's busy, they'll be moved to a busy list so it 
> can try again later.
> 
>  How bout incomming calls?  If a student wants to know what their 
> balance is, they can call in, choose "Balance" from the menu, enter 
> their student id, and have the Asterisk server query the database for 
> their balance and read it back to them.
> 
>  We also have satelite campuses in Springer and Santa Rosa.  We can use 
> the same system for them, with additional benifits.  When someone at our 
> main campus wants to call a student in Santa Rosa, the call can be 
> routed over the network to our Santa Rosa campus and out their line.  So 
> it's a free, local call.  We end up getting free calls to anywhere we 
> have network connectivity and a phone line.  The same works in reverse.  
> Students in Santa Rosa could dial a local, Santa Rosa number, and be 
> connected to our main campus over our network.  The call is free for the 
> student, and because they don't have to use our 1-800 number, it's free 
> for us as well.
> 
>  A few minutes ago I set up a tunnel between my laptop and work (needed 
> because SIP doesn't transverse NAT).  Phone quality seems just fine.  So 
> I can be sitting at the bar w/ my laptop, connected to their wireless, 
> and someone at work can dial my extension.  They will be connected 
> transparently to my laptop.
> 
>  Ok, this is all very nice in a small test enviornment, but how well 
> will it scale?  I don't know yet.  Total cost to replace our leased 
> equipment will be about $13K (less than a single year of leasing our 
> existing system).  This includes buying phones, hardware, interface 
> cards, etc.  So it makes sense financially, it gives us additional 
> abilities that we don't have yet.
> 
>  I'm requesting $500 for some phones and FXO/FXS boxes (to convert 
> between analog data and IP packets) to see how well it works together 
> and give us a change to test out some different brands/models of phones 
> to test for potential problems.  Whether or not we actually move to this 
> system remains to be seen (getting any changes through takes an act of 
> god), but it should be fun trying it out.
> 
>  If any of you are currently using an Asterisk system, I'd love to hear 
> about your experiences with it.  And if anyone is interested in setting 
> up their own system and has questions, feel free to contact me.
> 
> Matthew
> 
> 
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