ISPConfig module for WHMCS
Create a directory on your WHMCS server in the modules/servers directory and name the folder ispcfg3
Copy the file ispcfg3.php to your WHMCS modules/servers/ispcfg3 directory.
Further information can be found in the wiki https://github.com/cwispy/ispcfg3/wiki
Be sure to change the below option on a production system.
ini_set("display_errors", 1); to ini_set("display_errors", 0);