Fax to Email is not an inherant functionality of Call Manager or Unity. We use Cisco Rightfax at my company (I don't know what the new name is now), and it works very well. However any big time third party Fax Over IP solution should work. The hardest part of this, is user education, and what process you'll decide on for them to send faxes. Such as will they be faxing straight from Outlook via e-mail, or will they print to a fax printer? Some will want to receive faxes in their inbox, others will want it printed out. In either case, some will complain that it's not coming in to their real fax machine. So, the user experience is the main headache with something like this. The technology is fine.