When you try to open your PDF you get the message, "Adobe Reader could not open 'fax.pdf' because it is either not a supported file type or because the file has been damaged (for example, it was sent as an email attachment and wasn't correctly decoded)." it usually means that the fax was terminated by the sender just prior to finishing.  Have the sender resend the fax and have them make sure NOT to terminate the transaction until their fax machine confirms that the fax was sent correctly.  If this does not help, please let us know and we will attempt to recreate the file from what was received