Ubuntu 12.04 LTS

Fast installation

apt-get -y install php5-gd php5-mysql php5 php5-cli apache2 libapache2-mod-php5 tshark mtr mysql-server php5-mcrypt librsvg2-bin 
cd /usr/src/
wget http://sourceforge.net/projects/voipmonitor/files/6.5/voipmonitor-amd64-6.5.4-static.tar.gz /usr/src/
tar xzf voipmonitor*.tar.gz
cd voipmonitor*
./install-script.sh
mysqladmin create voipmonitor
cat cdrtable.sql | mysql voipmonitor
cd /var/www
wget "http://www.voipmonitor.org/download-gui?version=latest&major=5&festry" -O w.tar.gz
tar xzf w.tar.gz
mv voipmonitor-gui*/* ./
rm index.html
wget http://voipmonitor.org/ioncube/x86_64/ioncube_loader_lin_5.3.so -O /usr/lib/php5/20090626/ioncube_loader_lin_5.3.so
mkdir /var/spool/voipmonitor/
chown www-data /var/spool/voipmonitor/
wget http://sourceforge.net/projects/voipmonitor/files/wkhtml/0.10.0_rc2/wkhtmltoimage-x86_64 -O "/var/www/bin/wkhtmltoimage-x86_64"
chmod +x "/var/www/bin/wkhtmltoimage-x86_64"
wget http://sourceforge.net/projects/voipmonitor/files/wkhtml/0.10.0_rc2/wkhtmltopdf-x86_64 -O "/var/www/bin/wkhtmltopdf-x86_64"
chmod +x "/var/www/bin/wkhtmltopdf-x86_64"
wget http://voipmonitor.org/ioncube/x86_64/ioncube_loader_lin_5.3.so -O /usr/lib/php5/20090626/ioncube_loader_lin_5.3.so
echo "zend_extension = /usr/lib/php5/20090626/ioncube_loader_lin_5.3.so" > /etc/php5/apache2/conf.d/ioncube.ini
chown -R www-data /var/www
/etc/init.d/apache2 restart

Now go to http://yourserver/ and finish the installation (you need the key from [1]

Step by step

Installing packages - it will ask for mysql password - you can leave it blank or just notice it for later configuration

apt-get -y install php5-gd php5-mysql php5 php5-cli apache2 libapache2-mod-php5 tshark mtr mysql-server php5-mcrypt librsvg2-bin 

Installing sniffer

cd /usr/src/
wget http://sourceforge.net/projects/voipmonitor/files/5.5/voipmonitor-amd64-5.5-static.tar.gz /usr/src/
tar xzf voipmonitor*.tar.gz
cd voipmonitor*
./install-script.sh
mkdir /var/spool/voipmonitor/
chown www-data /var/spool/voipmonitor/

Creating database

mysqladmin create voipmonitor
cat cdrtable.sql | mysql voipmonitor

Installing IonCUBE extension for PHP which is neccessery for running voipmonitor GUI php scripts

wget http://voipmonitor.org/ioncube/x86_64/ioncube_loader_lin_5.3.so -O /usr/lib/php5/20090626/ioncube_loader_lin_5.3.so
echo "zend_extension = /usr/lib/php5/20090626/ioncube_loader_lin_5.3.so" > /etc/php5/apache2/conf.d/ioncube.ini

Installing WEB GUI

cd /var/www
wget "http://www.voipmonitor.org/download-gui?version=latest&major=5&festry" -O w.tar.gz
tar xzf w.tar.gz
mv voipmonitor-gui*/* ./
rm index.html
chown -R www-data /var/www
/etc/init.d/apache2 restart

Installing wkhtmltopdf binaries needed for GUI charts and reprots

wget http://sourceforge.net/projects/voipmonitor/files/wkhtml/0.10.0_rc2/wkhtmltoimage-x86_64 -O "/var/www/bin/wkhtmltoimage-x86_64"
chmod +x "/var/www/bin/wkhtmltoimage-x86_64"
wget http://sourceforge.net/projects/voipmonitor/files/wkhtml/0.10.0_rc2/wkhtmltopdf-x86_64 -O "/var/www/bin/wkhtmltopdf-x86_64"
chmod +x "/var/www/bin/wkhtmltopdf-x86_64"
wget http://voipmonitor.org/ioncube/x86_64/ioncube_loader_lin_5.3.so -O /usr/lib/php5/20090626/ioncube_loader_lin_5.3.so