About
Asterisk PBX is an Open Source Communications Server that handles voice, video and more with multi protocol and hardware interfaces. Additionally there are some related projects that are often thought of as part of the whole. DAHDI (Formally Zaptel), and LIBPRI are the first to come to mind.
Install
The installation of Asterisk on a computer running Linux can be quite easy. If you have developed software in the C programming language then it should make sense. There are two basic methods of installing. The first method is to compile and install from the source which grants you a level of control with updated versions. The second method is to use the packages from your Linux Distribution or the packages from the Digium Asterisk software reposititory.
Package Installation
Debian / Ubuntuaptitude install asteriskCentOS, Fedora, RedHat
yum install asterisk