This might help. This all works via ars. If you are using did numbers they can be set to go to the ars digits, a system speed call or what I have been doing as of late is to create a trusted extension that is rerouted always to a speed call. The speed call has my ars digits, my route absorbs them and adds <F>, which is the forwarded extension number. This method allows me to label what or for whom the fax box belongs to.