Another way to do it is to hand code it in a custom app like this...
exten => s,1,Authenticate(XXXXX)
exten => s,2,DISA(no-password,default)
Then simply drive the custom app from your IVR. This will give you DISA access to the sail context "default" which will allow you to dial anything you can dial from a regular extension in the default cluster.
Kind Regards
Selintra