Successful VOIP Over DSL, Part 5: Power Considerations

One of the great things about the traditional PSTN is that it keeps working when the power goes out. I’ve repeatedly read others recommending that people sustain traditional POTS service at least in part because of this fact. Their theory being that VOIP service isn’t sustained during a power outage. But this need not be the case given just a little forethought.

Prior to migrating to Asterisk we had been using a Panasonic KX-TG4000 KSU (seen left). This phone system has four FXO interfaces for analog lines.

It also featured a built-in battery backup so our phones stayed up through power outages. In migrating to VOIP within our home and office I felt it necessary to strive for this kind of reliability. It has certainly made my wife happier.

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When The Lights Go Down

A couple of days ago Garrett Smith posted on his blog entry stating, “One More Reason Pure VoIP is Not The Way to Go.” He goes on to describe a weather event that took out his power, internet access, and therefore his VOIP service.

I was born in the Niagara Region on the Canadian side of the border. I lived for 15 years in Toronto as well as 10 years in deep Northern Ontario. I’ve known winter in all its majesty.

In my former life as a kite enthusiast I made the drive from Buffalo, NY to Erie, PA through many a winter storm. And they certainly do get blasted from time-to-time in that part of the country.

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How To: Building an Embedded Asterisk PBX

This article was originally published at www.smallnetbuilder.com.

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.

Introduction

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).

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Successful VOIP Over DSL, Part 4: Traffic Shaping

My experience has been that the QoS mechanisms covered previously don’t provide a complete solution to the need for assured bandwidth when using VOIP over DSL. When the connection to the ISP becomes saturated for any reason VOIP traffic can be delayed which is always a problem. When managed QoS was combined with “traffic shaping” our VOIP phone service became much more reliable. This has proven to be true even on a very busy connection to my ISP.

Like the QoS mechanisms covered previously, traffic shaping is an edge process that occurs in your router. Traffic shaping is actually a process of reserving bandwidth specifically for selected applications. That bandwidth will not be used for other forms of internet access. As before, this tends to be most critical with outbound traffic where available bandwidth is most limited. It’s also true with inbound traffic, but this tends to be less of an issue.

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Successful VOIP Over DSL, Part 3: QoS Features In Small Routers

SOHO users like myself are unlikely to have high-end networking gear supporting their home office setups. My initial experience with VOIP over broadband involved using Vonage and a Linksys BEFSR-41 broadband router. At the time Vonage was the leading phone-over-broadband service and the BEFSR-41 was the leading SOHO router.

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