T 5.34 Deliberate re-programming of the destination keys on fax machines

To avoid the repetetive input of recurring fax numbers, some fax machines are equipped with programmable destination keys. During the transmission of fax messages to such recipients, the stored destination number is usually not checked. If unauthorised persons are able to re-program the destination keys and promptly forward the fax messages arriving at the new destination to the correct recipient, all fax traffic along this route can be monitored easily, perhaps without ever being detected.