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diff --git a/doc/chaniax.tex b/doc/chaniax.tex new file mode 100644 index 000000000..954e068b0 --- /dev/null +++ b/doc/chaniax.tex @@ -0,0 +1,84 @@ +\subsection{Introduction} + +This section is intended as an introduction to the Inter-Asterisk +eXchange v2 (or simply IAX2) protocol. It provides both a theoretical +background and practical information on its use. + +\subsection{Why IAX2?} + +The first question most people are thinking at this point is "Why do you +need another VoIP protocol? Why didn't you just use SIP or H.323?" + +Well, the answer is a fairly complicated one, but in a nutshell it's like +this... Asterisk is intended as a very flexible and powerful +communications tool. As such, the primary feature we need from a VoIP +protocol is the ability to meet our own goals with Asterisk, and one with +enough flexibility that we could use it as a kind of laboratory for +inventing and implementing new concepts in the field. Neither H.323 or +SIP fit the roles we needed, so we developed our own protocol, which, +while not standards based, provides a number of advantages over both SIP +and H.323, some of which are: + +\begin{itemize} + \item Interoperability with NAT/PAT/Masquerade firewalls + \begin{itemize} + \item IAX seamlessly interoperates through all sorts of NAT and PAT + and other firewalls, including the ability to place and + receive calls, and transfer calls to other stations. + \end{itemize} + \item High performance, low overhead protocol + \begin{itemize} + \item When running on low-bandwidth connections, or when running + large numbers of calls, optimized bandwidth utilization is + imperative. IAX uses only 4 bytes of overhead + \end{itemize} + \item Internationalization support + \begin{itemize} + \item IAX transmits language information, so that remote PBX + content can be delivered in the native language of the + calling party. + \end{itemize} + \item Remote dialplan polling + \begin{itemize} + \item IAX allows a PBX or IP phone to poll the availability of a + number from a remote server. This allows PBX dialplans to + be centralized. + \end{itemize} + \item Flexible authentication + \begin{itemize} + \item IAX supports cleartext, md5, and RSA authentication, + providing flexible security models for outgoing calls and + registration services. + \end{itemize} + \item Multimedia protocol + \begin{itemize} + \item IAX supports the transmission of voice, video, images, text, + HTML, DTMF, and URL's. Voice menus can be presented in both + audibly and visually. + \end{itemize} + \item Call statistic gathering + \begin{itemize} + \item IAX gathers statistics about network performance (including + latency and jitter, as well as providing end-to-end latency + measurement. + \end{itemize} + \item Call parameter communication + \begin{itemize} + \item Caller*ID, requested extension, requested context, etc are + all communicated through the call. + \end{itemize} + \item Single socket design + \begin{itemize} + \item IAX's single socket design allows up to 32768 calls to be + multiplexed. + \end{itemize} +\end{itemize} + +While we value the importance of standards based (i.e. SIP) call handling, +hopefully this will provide a reasonable explanation of why we developed +IAX rather than starting with SIP. + +\subsection{Configuration} + +For examples of a configuration, please see the iax.conf.sample in +your the /configs directory of you source code distribution. |