Hi spurdray and welcome to our forum,
there is no user option to default codes on this panel. The most significant code is the download code which is 8 digits long (default is 8480000) and is used for DL900 - NX-586/8 communication. Even if you knew the program (installer) code your panel might be locked for local (through keypad) programming. You have the following options :
1. Buy an NX-586(RS232) or NX-588(USB) interface and the NX unlocker software ($99).http://www.nxunlocker.com
2. Connect your panel to a working land line and let me modem-connect to your panel. There might be a chance your download code is the default (without a callback option enabled), so I could also default your program code to 9713 and disable the local programming lock if enabled. You could save money for the NX-586/8 interface (my service to you is free).
3. If I find the download code to be changed (from the previous step) then you have to purchase an NX-586/8 interface. Download a trial demo of Taltech's TCPcom software and install it on a PC or Laptop.
With this software I would be able to "see" your COM port as one of my physical ones on my computer. Keep tcp port 1000 forwarded and open through all firewalls you might have.
Before all, make sure to also install DL900 software and be able to communicate with the panel until the “Incorrect control access code!” window/message shows up. The COM port used for this short communication with your panel must be used inside TCPcom software. It will be the COM port shared to me. TCPcom software must run as a server service on your side. Again the unlocking of your panel is free.