Tech Blog - Here is a tutorial on how to modify osTicket to show ticket number on the thank you page, after ticket creation instead of showing "Ticket #XXXXXX has been created", do take note the Ticket# showing as XXXXX was intentional for security reason as on osTicket ticket number also serve as password for checking ticket status, however if your using osTicket on private installation this is not a big concern.
Go to your osTicket file mine is in /var/www/html/tickets
Take a backup of open.php
cp -p open.php open.php-back
Look for the line below
And replace with
osTicket is a widely-used and trusted open source support ticket system. It seamlessly routes inquiries created via email, web-forms and phone calls into a simple, easy-to-use, multi-user, web-based customer support platform. osTicket comes packed with more features and tools than most of the expensive (and complex) support ticket systems on the market. The best part is, it's completely free.