Traffic Shaping for VOIP: Visible Proof

m0n0mon Graph smallI just love it when things work as expected. Having been out of town for a couple of days I came back today and needed upload quite a few things to servers in the UK. As I was doing this the phone started to get busier. That implies that the VOIP systems are functional. Nice.

The fact that the call quality is really good tells me that my QoS and traffic shaping solution is working well. I had pinned my ADSL service with both upload (FTP) and download (syncing Outlook email) and the voip call quality was still excellent.

It’s kind of fun to watch m0n0mon graph my DSL traffic, and note when a call ends by the sudden change in data rate. This is clearly indicated by the drop in data flow noted on the left side of the m0n0mon image.

What Interests You?

I must admit that I’m more than a little surprised a what people read around here. The single most popular article is the one I wrote back in January 2006 about Building An Embedded Asterisk Server Using Astlinux On a Soekris Net4801. I would have thought that would have less appeal since it was published elsewhere over two years ago.

The next most popular articles are the series called A Beginners Guide To Successful VOIP Over DSL, most especially the posts on QoS and traffic shaping. People come by and read these things every day.

Hardware reviews are something that I’ve done many times over the years. Although deep in my past they were not technology related. These I will be doing again beginning with the Snom M3s. I need to be disciplined about using the phones for long enough to really learn about them in depth, and not just go with my first impressions. Even though the phones are in daily use the review will is a few weeks away.

Amongst my next topics I think I’ll be trying a SIP-to-GSM gateway. I’d like to provide my own 911 and 411 service by bridging calls over to my cellular account.

If you’ve got any ideas for topics or items for review let me know. I’m always open to suggestions.

A Beginners Guide To Successful VOIP Over DSL

For the past ten years I have worked from a home office full time. This has been the major motivation for my education in networking, and onward into VOIP technologies.

Since the middle of 2005 we have not used traditional land-lines (POTS) for either our home or office phones. Our transition to VOIP was not flawless, but with some lessons learned along the way the system has proven very reliable. Over the course of several posts I hope to pass on those lessons that have served us well so that others may also benefit.

The topics in the series are at present as follows:

In the telling of this tale I will mention a number of devices many of which are not the current state-of-the-art. This doesn’t matter. I’m relating to you the actual devices I used. The principles will hold true for any similar current device.

How To: Building an Embedded Asterisk PBX

This article was originally published at

Michael Graves
January 13, 2006

The Asterisk open source Voice over IP (VoIP) PBX is usually set up on a standalone PC. But Michael Graves shows how the combination of a special Asterisk distribution and a single board computer can provide a compact, quiet and low-power alternative.


Astlinux is a bundled distribution of the Asterisk open source iPBX private branch exchange (PBX) software and a Linux operating system. Originally developed by Mark Spencer at Digium, Asterisk is the leading open source software in the telephony/VoIP space. Asterisk excels at combining traditional TDM telephony capability – provided through hardware from Digium and others – with VOIPservices. These include call routing, media gateway, media server and SIP signaling capabilities.

The Asterisk user community has been growing tremendously over the past two years, especially since the v1.0 release in the fall of 2004. With that growth has come the development of new distributions that bundle suites of software tools, to ease the setup and administration of a new Asterisk system. Asterisk@Home and Xorcom Rapid are both fine examples of this sort of activity.

Astlinux was developed by Kristian Kielhofner, and intended to go in a fundamentally different direction. Astlinux provides an Asterisk installation on a Linux distribution that has been built from scratch and optimized for small format hardware platforms – it takes what is essentially an embedded systems approach to Linux and Asterisk. In this article, I’ll show you how to build an VoIP PBX using Astlinux and a Soekris Net4801 single board computer (SBC).

Continue reading “How To: Building an Embedded Asterisk PBX”