Voice over IP Overview

This text is an attempt to provide a concise overview of the VoIP technology and the protocols behind it. The most popular sections cover SIP: Introduction to SIP, SIP Messages, SIP Call Flow, and SIP — Session Description Protocol. The other pieces deal with digitization of voice (start with this one if you are new to VoIP), audio codecs, codec latency vs. bandwidth optimization, audio jitter (a bit of math here), the Real Time Protocol, introduction to H.323, description of H.323 call flow, and H.323 call signalling optimizations.

VoIP Overview Sections

Responsive Design, Finally!

This web site now has a responsive design. The readability of the texts published here should be greatly improved on tablets as well as smartphones. Kudos to HTML5 UP for their site templates!

Site Map Generator

This Python script is a platform-independent site map generator. It crawls a web site starting from a given URL and outputs XML sitemap file that you can use for Google or other search engines. The new version 1.1.0 adds support for the robots.txt file and the 'nofollow' tag.

Freemind Tutorial and Example Mind Maps

Have a look at the Freemind tutorial if you are new to the Freemind mind-mapping app (applies to Freeplane as well). As an example of how to describe a complex topic with a mind map, I'm adding two larger maps: One that describes a typical CRM system, the other one contains notes about use cases. Both available in the Freemind file format.