Since DSL frequencies are never carried on the output of a eMTA, the filter would never help.
You don't say if your using a stand alone fax machine, a combo printer / scanner / fax or the fax modem and fax software built into Windows 7.
Many times slowing down the baud rate in the fax settings will get the fax through.
You haven't even said if the fax machine / fax printer / fax modem is grabbing the phone line and dialing out or not. Is the other end even answering?
