Well, since I still don't have the name of the GUI you are using I can't help you do anything.

You need to take JohnP's advice and call whoever wrote the GUI to figure it out.

If you want something free and actually useful to use I would recommend looking at Elastix. It uses FreePBX as the configuration GUI and has a lot of provisioning tools for phones and other things. The maintainers of it also offer paid support directly in case you get stuck.