Normally the Fax and outlook is something done by the FAX server
and between the FAX server and CUCM you can have either H323 ICT trunk or SIP trunk if the FAX server support IP
if not the FAX server has to have a TDM card like T1/E1 and to be connected back to back to a Voce Gateway and form the Voce Gateway you can send the Call to PSTN or internally too
so call manager will responsible for the call routing form the FAX to PSTN for example
HTH
if helpful Rate