This part will cover installation Asterisk service on RHEL. Asterisk is open source software. More about that you can find on next site: Asterisk site

In this example we suppose that we have two offices, which are located in different city's . After installing system you should start update process. All testing are performed on RHEL 5.4 version. More about this OS you can find on next link: Red Hat site

There are two ways for installing Asterisk. One is from source code ( I will use this one) and second is installing just from rpm's. For both type of installation you should update your system and install some extra packages. IP address of Asterisk server is 192.168.0.10 and hostname of this machine is asterisk1

[root@asterisk1 rhn]# yum -y update
[root@asterisk1 rhn]# yum -y install gcc gcc-c++ kernel-devel bison openssl-devel libtermcap-devel ncurses-devel doxygen curl-devel newt-devel mlocate lynx tar wget nmap bzip2 mod_ssl crontabs vixie-cron speex speex-devel unixODBC unixODBC-devel libtool-ltdl libtool-ltdl-devel mysql-connector-odbc mysql mysql-devel mysql-server php-mysql php-mbstring php-mcrypt flex screen libxml2 libxml2-devel libtiff libtiff-devel