For the benefit of anyone searching for fax numbers in order to communicate with Equifax, Experian or TransUnion, these are currently working:
Equifax Fax Number: 888-826-0573
Experian Fax Number: 972-390-3838
TransUnion Fax Number: 610-546-4771
Please let us know if any of these numbers fail to work, and we'll continue to keep this thread updated as often as possible with the correct information.