Author Archives: David Chappell

Electrical Power and Power Loss

Basic Electrical Units A volt is a unit of electrical potential. Electrical potential in turn is the force which a power source (such as a battery) applies to a connected device in order to push electrons through it. Electrical potential … Continue reading

electricity

Communicating Clearly About Computing

Those of use who work in IT are frequently called upon to explain our work to people who are less familiar with computers than we are. It should be our goal to speak and write as clearly as possible. To … Continue reading

english, writing style

BIND and Invalid Zone Files: a Lurking Problem

It looks like Webmin lets you create DNS entries which BIND 9 does not like. When it sees one it refuses to load the whole zone and keeps what it has in RAM. This may go unnoticed for months until … Continue reading

dns, system administration

Draco’s Policies were Draconian

Have you every wondered why we call a harsh policy “draconian”? This is one of those words which comes from the name of a famous person.

language

Flowroute

I have been grieving ever since Voicepulse canceled its flexrate program and been looking for a new low-price provider with good quality.

asterisk, voip

Reducing Echo in Telephone Handsets

A common source of echo in VoIP phone systems is the telephone handsets. Of course, non-VoIP phone systems have this source of echo too, but it often is not so evident because without the buffering the echo delay is not … Continue reading

telephone, voip

How to be a Good VoIP Provider for Asterisk Users

There is more to being a good VoIP telephony provider for Asterisk users than simply offering the best balance of price and reliability. Usability is also very important. Here are some things which make for a service more convenient for … Continue reading

asterisk, telephone, voip

Is open source telephony a serious option?

I was recently asked whether anyone would every really consider replacing a tired old PBX with an open source system and whether we had any experience with Asterisk. Here is the answer I wrote, based on our experience here at … Continue reading

asterisk, opensource, telephone

Join the DUNDi cloud, call Europe!

Do you have an Asterisk box and an underutilized T1? Or do you have a large number of DID numbers on your PBX? Why not join a DUNDi cloud and trade access to your numbers or to your local calling … Continue reading

asterisk, voip, voip peering

My VoIP network

I run a VoIP network for my friends and family. There are phones at about 10 locations. Four of the locations have Asterisk servers. Three of the Asterisk servers are run in a redundant configuration. SIP query DNS to get … Continue reading

asterisk, voip