Enterprise 2007 is Office - and a Volume Licensed product the license for which is only valid within the organisation that purchased the license.
If you are not a member of that organisation, then the license is not valid, whatever the activation state.
Such licenses and products are not available to the general public through normal retail hannels.
If you purchased this product retail, complain to the vendor and demand a refund.
If you acquired it through somewhere like eBay, then it's almost certainly well beyond the time that complaining would be either useful or productive, as the vendor will probably have gone to pastures new.
If you acquired it through your employer or college, contact them for assistance.