Just a short one, here's my extension configuration for dialing ISN/ITAD extensions from freeswitch. Replace $${local_itad} with your ITAD. This will match all numbers dialled with a * in them, so you may need to modify it to your needs.
<extension name="isn">
<condition field="destination_number" expression="^(\d+\*\d+)$">
<action application="enum" data="${destination_number} freenum.org" />
<action application="set" data="effective_caller_id_number=${effective_caller_id_number}*$${local_itad}" />
<action application="bridge" data="${enum_auto_route}" />
</condition>
</extension>
