Centos 7

Create file /etc/systemd/system/voipmonitor.service

[Unit]
Description=VOIPmonitor tool for VOIP monitoring
After=syslog.target
After=network.target
After=mariadb.service
[Service]
Type=forking
ExecStart=/etc/init.d/voipmonitor start
ExecStop=/etc/init.d/voipmonitor stop
#Give a reasonable amount of time for the server to start up/shut down
TimeoutStartSec=0
TimeoutStopSec=180
#Place temp files in a secure directory, not /tmp?
PrivateTmp=false
[Install]
WantedBy=multi-user.target

Installation procedure

yum -y install httpd wireshark php php-gd php-mysql php-mbstring mtr php-process librsvg2 librsvg2-tools urw-fonts mariadb-server mariadb
systemctl start httpd.service
systemctl enable httpd.service
systemctl start mariadb.service
systemctl enable mariadb.service
mysql_secure_installation

#voipmonitor
cd /usr/src/
wget --content-disposition http://www.voipmonitor.org/current-stable-sniffer-static-64bit.tar.gz
tar xzf voipmonitor*.tar.gz
cd voipmonitor*
./install-script.sh
vim /etc/voipmonitor.conf
systemctl restart voipmonitor.service
#optionaly check that voipmonitor.service is running systemctl status voipmonitor.service

#GUI
cd /var/www/html 
wget "http://www.voipmonitor.org/download-gui?version=latest&major=5&allowed&phpver=54" -O w.tar.gz
tar xzf w.tar.gz 
mv voipmonitor-gui*/* ./
rm -f index.html
chown apache /var/spool/voipmonitor/
wget http://sourceforge.net/projects/voipmonitor/files/wkhtml/0.10.0_rc2/wkhtmltoimage-x86_64 -O "/var/www/html/bin/wkhtmltoimage-x86_64"
chmod +x "/var/www/html/bin/wkhtmltoimage-x86_64"
wget http://sourceforge.net/projects/voipmonitor/files/wkhtml/0.10.0_rc2/wkhtmltopdf-x86_64 -O "/var/www/html/bin/wkhtmltopdf-x86_64"
chmod +x "/var/www/html/bin/wkhtmltopdf-x86_64"
wget http://voipmonitor.org/ioncube/x86_64/ioncube_loader_lin_5.4.so -O /usr/lib64/php/modules/ioncube_loader_lin_5.4.so
echo "zend_extension = /usr/lib64/php/modules/ioncube_loader_lin_5.4.so" > /etc/php.d/ioncube.ini
chown -R apache /var/www/html
sed -i 's/SELINUX=enforcing/SELINUX=disabled/' /etc/selinux/config
setenforce 0
systemctl restart httpd.service

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