Hi Juan,
I am assuming you mean the default script that is used for the Application settings correct? That script is what is played if the main script fails for some reason. So if your caller calls into a script and for some reason that script fails, they will fall to the 'default' script which says something like "we're sorry, we are unable to complete your call".. or something of that nature.
If you wanted your callers to hear something custom like "Thank you for calling ABC bank, we are currently experiencing technical difficulties and will direct you to voicemail..." you could use some other script in place of the 'default' script.
This is all the 'default' script does. It will not deliver a call to CAD. It's used as an error play back script.
Hope this helps.
Mike
