- From a whistleblower privacy point of view, Facsimile Machines (fax) combine the worst tracking features of land line telephones with the wear and tear induced characteristic blemishes of photocopiers and printers
- Most models of Fax machine display or print at the bottom of each page or at least at the end of each transmission, a customisable message line which identifies the name of the company or organisation sending the fax, with its fax telephone number. If you are publishing scanned images of faxed documents, you should pay attention to the redaction or censorship of this line .
- Since the words and numbers are user programmable (i.e. easily faked), you should not jump to immediate conclusions as to the authenticity of a faxed document, simply on the basis of this return address / return fax data
- Since long distance phone calls , which can often be common with Faxes, cost money, there are built in electronic memory and / or printed log files available of the recent Fax transmissions ad receipts, with the identifying phone numbers and times and dates. This should be borne in mind if you do use a shared fax machine to send any whistleblowing documents to journalists or bloggers.
- If you are sending sensitive material via fax, there is a small, but finite risk of mis-dialling, and sending it off to the wrong number entirely, which may betray a whistleblower.
- Sometimes, a supposedly mis-dialled fax number, has in the past, been used as the "plausibly deniable" cover story, to make a deliberate leak look accidental or to add credibility to a deliberately misleading fake leak.
- It is common practice to print or scribble a Fax Cover sheet with addressing information (and often with pre-printed Return Fax data on it. This can give clues as to authenticity of seemingly accidental fax leaks.
- Many fax machines nowadays are effectively digital scanners (sometimes combined with photocopy and printer devices), or they eschew the process of scanning paper and simply convert , say Word document computer files into Facsimile format and then transmit them.
Such sophisticated Fax devices may very well keep copies of the original document data files or of the image scans in their internal memory or on their hard disks, in case the fax needs to be re-transmitted.
Fax gateways will also keep a log file of time and date when the copy was made, and details of the computer which send the fax, and, if there is some sort of electronic payment or internal accounting system, the department or people or the individual corporate client account (very common in large legal firms, for example) to which the fax costs are to be allocated..
Even when these files are apparently deleted or overwritten, they may not have entirely disappeared, and might well be recoverable through standard computer forensic techniques. Yet another reason for whistleblowers to be extremely careful when using fax machines.
- As with all heavily used office printing equipment, slight defects in manufacture, and heavy use, can induce characteristic blemishes on the output of a fax machine, which may provide sufficient clues to forensic investigators working for a major whistleblower leak inquiry, to track down the fax machine which was used to send whistleblowing revelations to a journalist or blogger etc.
Consider digitally cleaning up any scratches, or other blemishes on image scans of faxed documents, before publishing them.
- There are some positive points about Fax machine telephone lines in offices, from a whistleblower's point of view, as these can very often have special privileges compared with the other phones in the building e.g.
- they may be made available 24 hours a day, 365 days a year, when the other phones are disabled at night or at weekends and they can usually be used to make voice calls as well as to send faxes.
- they may also be allowed to make international calls, when the normal office phones require permission from the switchboard operator.
- they may be the only analog POTS phone lines left working in an otherwise VoIP office, and they could be used by a laptop computer user to dial out to another office or to for a dial-up Internet Connection, in order to send an email, which does not pass through the normal office internet gateway and its logfiles.