User guide

To understand why open standards are important, let us start by providing a simple definition of a
“standard.”
A standard is a set of rules, conditions, or requirements describing materials,
products, systems, services, or practices.
In telephony, technical standards have ensured that telephone exchanges around the globe can
interoperate with each other. Without standards a telephone system of one region might not
interoperate with another system a few kilometres away. Although many of the telephony standards are
publicly available, telephony has always been under the control of a few vendors capable of negotiating
contracts at regional or national levels. This fact might explain why it is extremely common to see the
same type of telephone equipment all over a particular country. Talking about telephony equipment has
always meant discussing technology built specifically to serve a single purpose, known as dedicated
hardware and software. Although the rules (or standards) that govern telephony have been relatively
open, the rules that govern the hardware have always been kept secret.
Open standards was one of the conditions needed to allow anyone to build telephony infrastructure, but
what created this new “revolution” was the possibility of emulating those expensive telephony systems
(hardware based) with a personal computer and software. All the required elements are now in place:
• we have access to the software and hardware to exchange phone calls
• we have an open and public network to exchange the calls (the Internet)
• we are able to adapt and modify all these elements to meet our own needs
3.3 Asterisk
Asterisk is a free and open source implementation of a telephone
exchange. The software allows a number of attached phones to make
calls to one another and to connect to the global telephony network.
The code was originally created by Mark Spencer (Digium) based on the ideas and previous work of
Jim Dixon (Zapata Telephony Project). The software and its many new features (including bug reports)
have been contributed by the open source community. Although Asterisk can run on several platforms,
GNU/Linux is the best-supported operating system.
To run Asterisk , you only need a personal computer (PC) but you need special hardware if you wish to
attach ordinary telephones or connect to the telephone network.
Page 8 TRICALCAR | www.wilac.net/tricalcar – Version: February 2008