Install dependencies:

	# yum -y install kernel-devel bison bison-devel ncurses ncurses-devel zlib zlib-devel openssl openssl-devel gnutls-devel gcc gcc-c++ make libxml2-devel

Download Asterisk and DAHDI:

	# wget http://www.asterisk.org/downloads/asterisk/releases/asterisk-1.6.2-current.tar.gz && wget http://downloads.asterisk.org/pub/telephony/dahdi-linux-complete/releases/dahdi-linux-complete-2.3.0.1+2.3.0.tar.gz

Extract Asterisk and DAHDI:

	# tar -xvzf asterisk-1.6.2-current.tar.gz && tar -xvzf dahdi-linux-complete-2.3.0.1+2.3.0.tar.gz

Build DAHDI:

	# cd dahdi-linux-complete-2.3.0.1+2.3.0
	# make all
	# make install
	# make config

Start DAHDI:

	# service dahdi start

Build Asterik:

	# cd asterisk-1.6.2.11
	# make clean
	# ./configure

Configure Asterisk build:

	# make menuselect
	# make
	# make install

Install sample files in /etc/asterisk:

	# make samples
	# make config

Verify the Asterisk installation:

	# safe_asterisk
	# asterisk -vvvvvr
	CLI> reload
	CLI> quit

Start Asterisk:

	# service asterisk start

Set Asterisk and DAHDI to start on boot:

	# chkconfig dahdi on
	# chkconfig asterisk on

Reference:
http://www.asteriskguru.com
http://nixjedi.com