A few weeks ago I wrote a response to Ruth’s article “How the Emergency Alert System has already been tested–and could be improved”. When I showed her my response and asked for help making it sound good (as you should already know I could keep several editors busy on a daily basis). She provided some very good insight on how to improve my writing (but I like words with ‘z’ in them) and also offered to publish the paper on the OpenSource.com website. How could I refuse such an offer? So here it is, the awesome response and plan for bringing the emergency alert system into the 21st century kicking an screaming, Building an Emergency Alert System for the 21st century.
Oh, and if you find any problems in the essay blame my editor.
A few years ago I setup an Asterisk (*) server at my house which ran for many years on a NSLU2. It was used as a proof of concept and included IAX2 and SIP connections (over VPN) to other people’s * servers. An elaborate dialplan and connections running all over the place made everything messy but fun.
Fast forward to a few weeks ago when I started working from home. I had a few choices about telephony in my office. I could have used the home phone but I definitely don’t want to give that number out to customers and coworkers. Then there’s the cellular phone that the company is picking up the tab on anyway but I’d like to conserve those minutes for customer emergencies. So it seemed that I had only a few choices left. I could have had the phone company “turn on” another circuit for me or I could roll my own. My inner geek was screaming at me. Now was the time I could use my * knowledge for good! Of course my * knowledge had dribbled out of my left ear over the last year or so since I really played with everything so I ran into a few roadblocks. Luckily I know people who are much smarter than me (and that I trust with sudo access to my server).
On my desk I’m running a Grandstream GXP-2000 (four line phone but how many people can I talk to at one time?) and I’m running CSipSimple on my Android device. I can call myself (and my wife) directly over the internal setup without touching an external line but what fun is that? I needed access to the PSTN so I could contact customers over the twisted pair. Well, I already have a Google Voice account with phone number that I had been using for work-related contacts, as well as some personal contacts, so it was an obvious choice. At Ohio Linux Fest one of the speakers talked about connecting * to Google Voice which further inspired me to make this happen.
Luckily for me the * community maintains instructions for doing such things right on the * wiki! It was almost as simple as copying and pasting the examples from the wiki to my config files. I did run into a few problems but did I mention I know people?
After a few tweaks (okay, probably more than a few tweaks but I’m telling this story) phones were ringing everywhere. I can dial out, dial in, and communicate with others everywhere now.
I’d like to take a moment to send good karma to Jared for helping me get everything straightened out and working.
I guess I should go call someone now…
Sparks’ Linux Journal by Eric “Sparks” Christensen is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License.
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The Fedora Talk project inspired me to get my Asterisk box back up and running again. Joat and I had been working on this project a few months ago but I gave up after thinking I couldn’t get a cheap VoIP. Joat pointed me to a phone that was around $40 and that sparked my interest again.
Tonight we got the kinks worked out so that our servers are linked together using IAX2 (pronounced Eeks) and we can communicate with no problems. I had attempted to create a SIP connection to the Fedora Talk server but there is where the problem lies. I can register to the server but I get authentication errors when I try to make a call through that “link”. It MIGHT be on the Fedora side but I’ll have to talk someone on the Infrastructure Team to find out.
Otherwise, the next step to this whole mess is securing the links between Joat’s server and my server. There is the talk about encrypting just the IAX2 link but that would leave some red traffic on the SIP side of the house and that won’t help me once I move to my next phase which will include a lot of SIP traffic which HAS to be encrypted.
So the experiment continues. I’ll write more as my work continues.
When my alarm went off at 5 AM this morning it interrupted a dream I was having about Asterisk. While I can’t quite remember the specifics I’m sure it included the perfect settings for my extensions.conf, sip.conf, and iax.conf files. Just another reason to keep a piece of paper next to the bed to make middle-of-the-night notes.
So Joat and I worked over IRC to get Asterisk setup on my computer. Running Fedora 8, the installation was quite easy. What wasn’t so easy was getting my head wrapped around the three big files (extensions, sip, and iax) that control Asterisk. With a semi-guru helping me do the configuration, understanding Asterisk wasn’t too bad (maybe I should read the book).
I have big plans to link my family together using SIP phones. Of course this is nothing more than a big experiment for me. If it works then I’ll be happy.
I’m still waiting for my FWD account to be setup with IAX capabilities. As soon as that happens the real fun begins. I’ll talk more about my setup later.