Download a CentOS 7 ISO from here, burn the image on a physical DVD/CDRom/USB Thumb Drive.
Insert the boot media into your Intel or AMD computer/virtual server and power it up.
Press enter on the boot screen to begin sipXcom installation
On Configure TCP/IP screen, select Manual Configuration under Enable IPv4 support and then select OK.
On Manual TCP/IP Configuration screen, set the static IPv4 address and subnet mask of the sipXcom server, gateway and name server and click OK.
Select the language, keyboard and time zone to be used during the installation.
Set a root password for sipXcom server.
Click Next on Boot Loader screen.
After CentOS finishes installing, check Next.
Don't forget to take your DVD out of the drive or eject the virtual drive...
Initial sipXcom Configuration
Login to the system as root with the password you provided earlier and continue to configure sipXcom starting with Network Settings. Enter "n" response to "Would you like to configure your system's network settings?" and continue entering the rest of the items.