Matt G. Watson

HowTo: Asterisk AlarmReceiver with DSC Alarm

Synopsis

This HowTo is a guide on using Asterisk’s AlarmReceiver() application to make Asterisk act as an Ademco Contact ID alarm monitoring station. In short this application is capable of receiving calls from your alarm panel every time an event occurs on your system. This is essentially a complete home grown self-monitored alarm setup.

I should mention upfront that this application is not approved by the Underwriter’s Laboratory and as such, any insurance benefits you have from having an alarm system will probably be null and void with your insurance company if you go down this path. Personally, I think alarm systems in homes that do not utilize cellular connections are useless anyways. Landlines are too easy to disconnect on most homes… rendering the alarm monitoring useless.

Additionally, this guide assumes that your system is already programmed for monitored and that you just want to interface it with Asterisk.

How To: Basic QoS on Vyatta with DSCP for VoIP

Synopsis

So you’ve setup a VoIP phone system, but now you want to setup QoS on your router to prioritize your VoIP packets. This is imperative if you intend on running VoIP over any kind of WAN links like I do. Call quality might suffer otherwise - especially when that staff member decides he wants to donwload that 300mb service pack at work instead of using his own connection at home. I’ll show you here how you can solve this problem by using QoS on your Vyatta router.

My network looks something like this:

As you can see, I have 5 independent sites, the left side being my datacenter, and the right being individual sites where are staff work out of. Each site on the right has a Vyatta VC4 router running as its gateway and each of these sites are running Aastra IP phones which connect to our Asterisk PBX server running in the data center.

Anyways… onto the nitty gritty. Click the article title or the read more link below to read on.

Vyatta Referral Program Now Available to non-US Residents

Well I myself just attempted to sign up for the Vyatta referral program last evening. I got half way through filling out the form and was sad to discover that the program was only available to US residents.

Believe it or, but I was just informed this afternoon by email from Tom McCafferty, Director of Marketing for Vyatta Inc, that the referral program is now available to non-US residents starting today!

Matt,

You have incredible timing. I was in the process of updating some of our partner programs last night when your e-mail came through. The web referral program is now available to users outside of the US. You can apply at http://www.vyatta.com/partners/webref.php

I encourage any of you interested in this program to sign up for the Vyatta referral program.

This would probably also be a good time to encourage those of you unfamiliar with Vyatta to download a free copy today and check it out. Whether you are just using a Linux box as a router doing IP Masquerading / NAT, or your using Cisco routers or PIX / ASA firewalls, I really recomend you give Vyatta a try, I think you’ll be incredibly impressed. If you are using Linux boxes as routers, I think you’ll really appreciate the streamlined configuration that Vyatta gives you using its Fusion CLI. If you are thinking about purchasing some Cisco gear, you’ll be even more impressed with how Vyatta is competing with Cisco at a fraction of the cost!

Vyatta offers its product in several forms, there is a free community edition, a subscription edition which includes enterprise support, and Vyatta appliances.

How To: Tune rxgain / txgain for Zaptel / DAHDI FXO interfaces on Asterisk PBX

Synopsis

This will be a quick and dirty tutorial on how to properly tune your Zaptel / DAHDI FXO interfaces on Asterisk via the Zapata channel interface chan_zap.

The purpose of tuning your FXO interfaces is first of all, to have proper audio levels on your FXO PSTN interfaces. However, my initial motivation for tuning my interfaces was to reduce the awful hybrid echo that was being caused on my FXO interfaces. The short of what hybrid echo is, is that there is a device in telco switches called a hybrid. Essentially what this device does is convert your single pair copper that connects to your house/office into a 2-pair connection, 1 pair that carries the receive audio, and 1 that carries the transmit. Telco’s do this because they need to amplify the signals independently for carrying calls over long distances. Unfortunately due to the nature of this device, it causes electrical leakage which causes the echo.

When using only regular analog phones, the echo created by the hybrid is still present, but there is such a short delay, it sounds like regular sidetone. When we enter the VoIP world, the delay increases due to processing and IP network stuff. This delay is not large generally, but its large enough that it becomes very obvious that you are hearing an echo of yourself. To help solve this we have echo cancelers, but echo cancelers can only do so much, the better the signal we can get to begin with, the easier the job the echo canceler has. To get a clean signal we need to adjust our rxgain and txgain values in zapata.conf for Asterisk.