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VoIP Protocols: Introducing SIP

http://www.toncar.cz/Tutorials/VoIP/VoIP_Protocols_Introducing_SIP.html

VoIP Protocols: Introducing SIP. The Session Initiation Protocol (SIP for short) is a Voice over IP protocol designed by the Internet Engineering Task Force. SIP was created by the MMUSIC. Group of the IETF (MMUSIC stands for Multi-party Multimedia Session Control). Formally, the protocol is intended for creating, modifying and terminating sessions with one or more participants. The sessions are mainly VoIP telephone calls or conferences. The first version of SIP was published in 1999 in RFC2543. In SIP&...

toncar.cz

Getting Started with Freemind

http://www.toncar.cz/Tutorials/MindMaps/getting_started_with_freemind.html

Getting Started with Freemind. This text is intended to help people who would like to start using the Freemind application to create mind maps. The tutorial works best if you try the individual steps in Freemind as you read. If you do not have Freemind readily available, I recommend that you at lest look at the Flash variants of the examples — these are available via the flash. Links under each example. The mm. The Freemind application.). Create a new map: Select File. In the menu or press Ctrl-N. Once m...

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VoIP Protocols: SIP - Session Description Protocol

http://www.toncar.cz/Tutorials/VoIP/VoIP_Protocols_SIP_Session_Description_Protocol.html

VoIP Protocols: SIP — Session Description Protocol. Let us have a look at the last protocol component that SIP needs in order to successfully establish a call. This last component is the Session Description Protocol. Or SDP for short. The Session Description Protocol was first published in 1998 in RFC2327. One year before SIP itself. The protocol was updated in 2006 with RFC4566. Like SIP, SDP is also a product of the MMUSIC working group. Aside from SIP, SDP was also used in Mbone. As you can see in thi...

toncar.cz

VoIP Basics: About Jitter

http://www.toncar.cz/Tutorials/VoIP/VoIP_Basics_Jitter.html

VoIP Basics: About Jitter. In this series, I have already mentioned jitter twice (in Codec Latency vs. Bandwidth Optimization. And in the piece about the Real Time Protocol. So I guess we should have a closer look what jitter is and how to deal with it. If you ever experimented with the program ping. The formula for estimating jitter is as follows (if you are not much into math, skip to jitter buffer explanation. J(i) = J(i-1) ( D(i-1,i) - J(i-1) )/16. The estimator computes jitter iteratively. To es...

toncar.cz

VoIP Overview

http://www.toncar.cz/Tutorials/VoIP/index.html

Voice over IP Overview. Voice over IP Basics. Converting Voice to Digital Form. Overview of Audio Codecs. Codec Latency vs. Bandwidth Optimization. Voice over IP Protocols. About the Real Time Protocol. VoIP Protocols: Introducing H.323. VoIP Protocols: H.323 Call Flow. VoIP Protocols: H.323 Call Signalling Optimizations. VoIP Protocols: Introducing SIP. VoIP Protocols: SIP Messages. VoIP Protocols: SIP Call Flow. VoIP Protocols: SIP — Session Description Protocol. Voice over IP Overview.

toncar.cz

VoIP Basics: Converting Voice to Digital Form

http://www.toncar.cz/Tutorials/VoIP/VoIP_Basics_Converting_Voice_to_Digital.html

VoIP Basics: Converting Voice to Digital Form. Are you interested in Voice over IP? Would you like to know more about its background? This text begins a series that should shed some light on it. Let's start with the beginning. VoIP sends digitized voice across computer networks. So how do we convert voice to the digital form? Sampling is about the sampling rate — i.e. how many samples per second you use to encode the sound. Figure 1: Analog signal. Figure 2: Digitized signal. It turns out 8-bit samples d...

toncar.cz

Open Source Sitemap Generator

http://www.toncar.cz/opensource/sitemap_gen.html

This software 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 (via Google Webmaster Tools. Or other search engines. Site maps are useful for SEO — you can give the search engine hints about what pages it can index at web your site. The site map generator program is published under GNU General Public License. And will not crawl into directories that are disallowed in the robots.txt. The script is mainly u...

toncar.cz

toncar.cz

http://www.toncar.cz/index.html

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. 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. A bit of math here), the Real Time Protocol. Introduction to H.323. Description of H.323 call flow. Responsive Design, Finally!

toncar.cz

VoIP Protocols: SIP Messages

http://www.toncar.cz/Tutorials/VoIP/VoIP_Protocols_SIP_Messages.html

VoIP Protocols: SIP Messages. As mentioned before, SIP is a text-based protocol. The formatting of SIP messages is based on the syntax of HTTP version 1.1. There are two types of messages: requests and responses. The format of a request is as follows:. Request headers ( several lines. Message body ( carries the Session Description Protocol message. In the message, end of line is always denoted with the two octets CR. Request headers ( several lines. Let's have a look at an actual SIP message:. The reques...